CDK_AWS_PARTITION: Does not fix the OIDC region and audience.

Hi,

Setting the environment variable `CDK_AWS_PARTITION` as specified here: [AWS China partition support](https://github.com/cdklabs/cdk-pipelines-github?tab=readme-ov-file#aws-china-partition-support), does not make sure that the `audience` and `aws-region` of this action: [aws-actions/configure-aws-credentials@v4](https://github.com/marketplace/actions/configure-aws-credentials-action-for-github-actions) are configured correctly.

This results in the following:

pipeline-definition.yml

```yaml
# AUTOMATICALLY GENERATED FILE, DO NOT EDIT MANUALLY.
# Generated by AWS CDK and [cdk-pipelines-github](https://github.com/cdklabs/cdk-pipelines-github)

name: deploy-china-partition
on:
push:
branches:
- main
workflow_dispatch: {}
jobs:
# ... other steps
Assets-FileAsset1:
name: Publish Assets Assets-FileAsset1
needs:
- Build-Build
permissions:
contents: read
id-token: write
runs-on: ubuntu-latest
outputs:
asset-hash: ${{ steps.Publish.outputs.asset-hash }}
steps:
- name: Download cdk.out
uses: actions/download-artifact@v4
with:
name: cdk.out
path: cdk.out
- name: Install
run: npm install --no-save cdk-assets
- name: Authenticate Via OIDC Role
uses: aws-actions/configure-aws-credentials@v4
with:
aws-region: us-west-1
role-duration-seconds: 1800
role-skip-session-tagging: true
role-to-assume: arn:aws-cn:iam::000000000000:role/DummyOIDCRole
- id: Publish
name: Publish Assets-FileAsset1
run: /bin/bash ./cdk.out/assembly-DummyStage/publish-Assets-FileAsset1-step.sh
# ... other steps

```

The `aws-region` part can be fixed by setting [publishAssetsAuthRegion](https://github.com/cdklabs/cdk-pipelines-github/blob/main/src/pipeline.ts#L214), when creating the pipeline. However the audience is not set to `sts.amazonaws.com.cn` which is a requirement for the OIDC authentication to work: [OIDC Audience](https://github.com/marketplace/actions/configure-aws-credentials-action-for-github-actions#oidc-audience). Because of this the github action to assume the OIDC role will fail.

Relevant issues:
* [ Add support for aws-cn partition #820 ](https://github.com/cdklabs/cdk-pipelines-github/issues/820)

## Reproducible python code:

requirements.txt

```
aws-cdk-lib==2.154.0
constructs>=10.0.0,<11.0.0
cdk-pipelines-github
```

cdk.json

```json
{
"app": "python3 app.py",
"watch": {
"include": [
"**"
],
"exclude": [
"README.md",
"cdk*.json",
"requirements*.txt",
"source.bat",
"**/__init__.py",
"**/__pycache__",
"tests"
]
},
"context": {
"@aws-cdk/aws-lambda:recognizeLayerVersion": true,
"@aws-cdk/core:checkSecretUsage": true,
"@aws-cdk/core:target-partitions": [
"aws",
"aws-cn"
],
"@aws-cdk-containers/ecs-service-extensions:enableDefaultLogDriver": true,
"@aws-cdk/aws-ec2:uniqueImdsv2TemplateName": true,
"@aws-cdk/aws-ecs:arnFormatIncludesClusterName": true,
"@aws-cdk/aws-iam:minimizePolicies": true,
"@aws-cdk/core:validateSnapshotRemovalPolicy": true,
"@aws-cdk/aws-codepipeline:crossAccountKeyAliasStackSafeResourceName": true,
"@aws-cdk/aws-s3:createDefaultLoggingPolicy": true,
"@aws-cdk/aws-sns-subscriptions:restrictSqsDescryption": true,
"@aws-cdk/aws-apigateway:disableCloudWatchRole": true,
"@aws-cdk/core:enablePartitionLiterals": true,
"@aws-cdk/aws-events:eventsTargetQueueSameAccount": true,
"@aws-cdk/aws-iam:standardizedServicePrincipals": true,
"@aws-cdk/aws-ecs:disableExplicitDeploymentControllerForCircuitBreaker": true,
"@aws-cdk/aws-iam:importedRoleStackSafeDefaultPolicyName": true,
"@aws-cdk/aws-s3:serverAccessLogsUseBucketPolicy": true,
"@aws-cdk/aws-route53-patters:useCertificate": true,
"@aws-cdk/customresources:installLatestAwsSdkDefault": false,
"@aws-cdk/aws-rds:databaseProxyUniqueResourceName": true,
"@aws-cdk/aws-codedeploy:removeAlarmsFromDeploymentGroup": true,
"@aws-cdk/aws-apigateway:authorizerChangeDeploymentLogicalId": true,
"@aws-cdk/aws-ec2:launchTemplateDefaultUserData": true,
"@aws-cdk/aws-secretsmanager:useAttachedSecretResourcePolicyForSecretTargetAttachments": true,
"@aws-cdk/aws-redshift:columnId": true,
"@aws-cdk/aws-stepfunctions-tasks:enableEmrServicePolicyV2": true,
"@aws-cdk/aws-ec2:restrictDefaultSecurityGroup": true,
"@aws-cdk/aws-apigateway:requestValidatorUniqueId": true,
"@aws-cdk/aws-kms:aliasNameRef": true,
"@aws-cdk/aws-autoscaling:generateLaunchTemplateInsteadOfLaunchConfig": true,
"@aws-cdk/core:includePrefixInUniqueNameGeneration": true,
"@aws-cdk/aws-efs:denyAnonymousAccess": true,
"@aws-cdk/aws-opensearchservice:enableOpensearchMultiAzWithStandby": true,
"@aws-cdk/aws-lambda-nodejs:useLatestRuntimeVersion": true,
"@aws-cdk/aws-efs:mountTargetOrderInsensitiveLogicalId": true,
"@aws-cdk/aws-rds:auroraClusterChangeScopeOfInstanceParameterGroupWithEachParameters": true,
"@aws-cdk/aws-appsync:useArnForSourceApiAssociationIdentifier": true,
"@aws-cdk/aws-rds:preventRenderingDeprecatedCredentials": true,
"@aws-cdk/aws-codepipeline-actions:useNewDefaultBranchForCodeCommitSource": true,
"@aws-cdk/aws-cloudwatch-actions:changeLambdaPermissionLogicalIdForLambdaAction": true,
"@aws-cdk/aws-codepipeline:crossAccountKeysDefaultValueToFalse": true,
"@aws-cdk/aws-codepipeline:defaultPipelineTypeToV2": true
}
}
```

app.py

```python
#!/usr/bin/env python3

import aws_cdk as cdk
import os

from constructs import Construct
from cdk_pipelines_github import GitHubWorkflow, AwsCredentials, JsonPatch

app = cdk.App()

TEST_ACCOUNT_ID = os.environ['TEST_ACCOUNT_ID']
TEST_OIDC_ROLE_NAME = os.environ['TEST_OIDC_ROLE_NAME']

class DummyStack(cdk.Stack):
def __init__(self, scope: Construct, construct_id: str, **kwargs) -> None:
super().__init__(scope, construct_id, **kwargs)

cdk.aws_sqs.Queue(
self,
"IssueGithubPipelinesQueue",
visibility_timeout=cdk.Duration.seconds(300),
)

class DummyPipelineStage(cdk.Stage):
def __init__(self, scope: Construct, construct_id: str, **kwargs) -> None:
super().__init__(scope, construct_id, **kwargs)

DummyStack(self, f"TestStack", **kwargs)

github_pipeline = GitHubWorkflow(
app,
"GithubPipeline",
synth=cdk.pipelines.ShellStep(
"Build",
commands=[
"npm install -g aws-cdk",
"python -m pip install -r requirements.txt",
"cdk synth",
],
),
aws_creds=AwsCredentials.from_open_id_connect(
git_hub_action_role_arn=f"arn:aws-cn:iam::{TEST_ACCOUNT_ID}:role/{TEST_OIDC_ROLE_NAME}"
),
workflow_name="deploy-china-partition",
workflow_path=".github/workflows/deploy-china-partition.yml",
publish_assets_auth_region="cn-northwest-1",
)
github_pipeline.workflow_file.patch(
JsonPatch.add(
'/env',
{
'AWS_STS_REGIONAL_ENDPOINTS' : 'regional',
'TEST_ACCOUNT_ID' : '${{ vars.TEST_ACCOUNT_ID }}',
'TEST_OIDC_ROLE_NAME' : '${{ vars.TEST_OIDC_ROLE_NAME }}',
}
)
)
wave = github_pipeline.add_wave("MultiRegion")

stage = DummyPipelineStage(
app,
"DummyStage",
env=cdk.Environment(account=TEST_ACCOUNT_ID, region="cn-north-west-1"),
)

wave.add_stage(
stage,
)

app.synth()
```

### Version
Python 3.10.0
cdk-pipelines-github version: cdk-pipelines-github==0.4.124

### Modifications/environment/deployment
I Have made no modifactions to code environment or deployment that should affect this.

### Issue
Setting the environment variable `CDK_AWS_PARTITION` does not setup the OIDC Github Action correctly.

### Local testing:
0. (Make sure you have python, pip and cdk isntalled).
1. copy, `cdk.json`, `app.py`, and `requirements.txt`
2. `python3 -m venv .venv`
3. `source .venv/bin/activate`
4. `pip install -r requirements.txt`
5. `export TEST_ACCOUNT_ID= && export TEST_OIDC_ROLE_NAME=`
6. `cdk synth`

View the output workflow file in `.github/workflows/`.

### EDITS:
1. Updated the python file by changing the env variables for the workflow. Added cdk.json. Added description on how to test locally.