feat: add post-checkout-command input to action

Author: rcmdnk

README.md

@@ -9,6 +9,7 @@ GitHub Action for Python (Poetry, pytest with coverage and  linters with prek/pr
 Name | Description | Default | Required
 -|:-|-|-
 checkout| Set `1` to run [checkout](https://github.com/marketplace/actions/checkout). | `1` | No
+post-checkout-command| Optional shell command(s) to run right after checkout (only when `checkout` is `1`). Multiple commands can be passed as a multi-line string (e.g. with YAML `\|`). The value is interpolated into a `bash` script, so pass only trusted content. | `''` | No
 set-python| Set `1` to run [setup-pytyon](https://github.com/marketplace/actions/setup-python). | `1` | No
 python-version| `python-version` for setup-python. | `3.12` | No
 setup-type| Python environment setup type (`poetry` `uv`, or `pip`.). | `poetry` | No

action.yml

@@ -10,6 +10,10 @@ inputs:
     description: 'Set 1 to run checkout.'
     default: '1'
     required: true
+  post-checkout-command:
+    description: 'Optional shell command(s) to run right after checkout. Multiple commands can be passed as a multi-line string.'
+    default: ''
+    required: false
   setup-python:
     description: 'Set 1 to run setup-python.'
     default: '1'
@@ -126,6 +130,13 @@ runs:
       with:
         persist-credentials: false
         fetch-depth: 0
+    - name: Run post-checkout command
+      if: ${{ inputs.checkout == '1' && inputs.post-checkout-command != '' }}
+      run: |
+        echo "::group::post-checkout command"
+        ${{ inputs.post-checkout-command }}
+        echo "::endgroup::"
+      shell: bash
     - name: Install poetry
       if: ${{ inputs.setup-type == 'poetry' }}
       run: |