push workflow not triggered in v3.

### Prerequisites

- [X] I have written a descriptive issue title
- [X] I have searched existing issues to ensure the regression has not already been reported

### Last working version

2.x

### Stopped working in version

3.x

### Node.js version

12.x

### Operating system

Linux

### Operating system version (i.e. 20.04, 11.3, 10)

20.04

### 💥 Regression Report

Now that v3 directly merges the pull request in the workflow without using an external app no push workflow is triggered.

In v2 once a dependabot pull request got merged any workflows listening on the push event were triggered.

### Steps to Reproduce

## automerge.yml

```yaml
name: automerge

on:
pull_request:
branches:
- main

jobs:
automerge:
runs-on: ubuntu-latest
permissions:
pull-requests: write
contents: write
if: ${{ github.actor == 'dependabot[bot]' }}
steps:
- uses: fastify/github-action-merge-dependabot@v3.0.2
with:
github-token: ${{ secrets.GITHUB_TOKEN }}
```

## ci.yml

```yaml
name: ci

on:
push:
branches:
- main

jobs:
ci:
runs-on: ubuntu-latest
steps:
- run: |
echo hello
```

### Expected Behavior

### `ci.yml` to be called.

I am unsure how/if this can be fixed as dependabot workflows have no access to other secrets other than the default `GITHUB_TOKEN`.