Error: argument `targetPort` only works if the container app does not exist yet

When you set the `targetPort` argument in the GitHub Action for deploying Container Apps on Azure, the initial deployment succeeds, but subsequent updates fail.

Here's an example configuration that triggers the issue:

```yaml
- name: Deploy Container App
uses: azure/container-apps-deploy-action@v2
with:
containerAppName: test-app
resourceGroup: [...resourceGroup]
imageToDeploy: [...imageUrl]
targetPort: 8080
```

**Identified Issue:**

The root of the problem seems to be the Azure CLI command `az containerapp update`, which lacks support for the `target-port` argument. Consequently, this Action defaults to using the `up` command for both initial deployments and updates. However, if the app is already running, attempting an update with the `up` command and a specified `target-port` results in a `Forbidden` error:

```text
/usr/bin/az containerapp up [...] --target-port 8080
ERROR: Operation returned an invalid status 'Forbidden'
```

As the ingress setup is only needed during creation, this Action should skip the `targetPort` and only update the container or (if specified) delete and re-create the container if the `targetPort` changed

Start with the GitHub Action deployment flow and reproduce the example using `targetPort` with `az containerapp up`. Compare the initial deployment path with updates using `az containerapp update`, and verify that an existing app updates without the Forbidden error while initial creation still configures the target port.

Written by the indexing model from the issue text.