Remove last use of installPython

- Add explicit `setup-python` step with condition to the workflow that was still using it
- This allows simplifying the logic in `sync.ts`

.github/workflows/__multi-language-autodetect.yml

@@ -35,11 +35,6 @@ on:
         description: The version of Go to install
         required: false
         default: '>=1.21.0'
-      python-version:
-        type: string
-        description: The version of Python to install
-        required: false
-        default: '3.13'
   workflow_call:
     inputs:
       dotnet-version:
@@ -52,17 +47,12 @@ on:
         description: The version of Go to install
         required: false
         default: '>=1.21.0'
-      python-version:
-        type: string
-        description: The version of Python to install
-        required: false
-        default: '3.13'
 defaults:
   run:
     shell: bash
 concurrency:
   cancel-in-progress: ${{ github.event_name == 'pull_request' || false }}
-  group: multi-language-autodetect-${{github.ref}}-${{inputs.dotnet-version}}-${{inputs.go-version}}-${{inputs.python-version}}
+  group: multi-language-autodetect-${{github.ref}}-${{inputs.dotnet-version}}-${{inputs.go-version}}
 jobs:
   multi-language-autodetect:
     strategy:
@@ -124,11 +114,6 @@ jobs:
         with:
           go-version: ${{ inputs.go-version || '>=1.21.0' }}
           cache: false
-      - name: Install Python
-        if: matrix.version != 'nightly-latest' || !matrix.version
-        uses: actions/setup-python@v6
-        with:
-          python-version: ${{ inputs.python-version || '3.13' }}
       - name: Prepare test
         id: prepare-test
         uses: ./.github/actions/prepare-test
@@ -136,6 +121,14 @@ jobs:
           version: ${{ matrix.version }}
           use-all-platform-bundle: 'false'
           setup-kotlin: 'true'
+      - name: Install Python 3.13 for older CLI versions
+        # We need Python 3.13 for older CLI versions because they are not compatible with Python 3.14 or newer.
+        # See https://github.com/github/codeql-action/pull/3212
+        if: matrix.version != 'nightly-latest' && matrix.version != 'linked'
+        uses: actions/setup-python@v6
+        with:
+          python-version: '3.13'
+
       - name: Use Xcode 16
         if: runner.os == 'macOS' && matrix.version != 'nightly-latest'
         run: sudo xcode-select -s "/Applications/Xcode_16.app"

pr-checks/checks/multi-language-autodetect.yml

@@ -4,9 +4,16 @@ operatingSystems: ["macos", "ubuntu"]
 env:
   CODEQL_ACTION_RESOLVE_SUPPORTED_LANGUAGES_USING_CLI: true
 installGo: true
-installPython: true
 installDotNet: true
 steps:
+  - name: Install Python 3.13 for older CLI versions
+    # We need Python 3.13 for older CLI versions because they are not compatible with Python 3.14 or newer.
+    # See https://github.com/github/codeql-action/pull/3212
+    if: matrix.version != 'nightly-latest' && matrix.version != 'linked'
+    uses: actions/setup-python@v6
+    with:
+      python-version: "3.13"
+
   - name: Use Xcode 16
     if: runner.os == 'macOS' && matrix.version != 'nightly-latest'
     run: sudo xcode-select -s "/Applications/Xcode_16.app"