Fix GitHub Actions Python 3.14.0-freethreaded setup issues

- Remove invalid '3.14.0-freethreaded' version string from matrix
- Update macOS runner from macos-13 to macos-14 for better compatibility
- Add dedicated test-freethreaded job with proper freethreaded Python builds
- Use correct architecture-specific download URLs from versions manifest
- Ensure freethreaded Python testing works across all platforms

Author: vinitkumar

.github/workflows/pythonpackage.yml

@@ -28,11 +28,11 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        python-version: [pypy-3.10, pypy-3.11, '3.10', '3.11', '3.12', '3.13', '3.14.0', '3.14.0-freethreaded']
+        python-version: [pypy-3.10, pypy-3.11, '3.10', '3.11', '3.12', '3.13', '3.14.0']
         os: [
           ubuntu-22.04,
           windows-2022,
-          macos-13,
+          macos-14,
         ]
     steps:
     - uses: actions/checkout@v4
@@ -142,3 +142,82 @@ jobs:
     - name: Run mypy
       run: mypy json2xml tests
 
+  test-freethreaded:
+    runs-on: ${{ matrix.os }}
+    strategy:
+      fail-fast: false
+      matrix:
+        include:
+          - os: ubuntu-22.04
+            python-version: '3.14.0'
+            arch: x64
+            platform: linux
+          - os: windows-2022
+            python-version: '3.14.0'
+            arch: x64
+            platform: win32
+          - os: macos-14
+            python-version: '3.14.0'
+            arch: x64
+            platform: darwin
+    steps:
+    - uses: actions/checkout@v4
+      with:
+        persist-credentials: false
+
+    - name: Download and setup Python ${{ matrix.python-version }} (freethreaded)
+      run: |
+        if [ "${{ matrix.platform }}" = "linux" ]; then
+          wget -O python.tar.gz "https://github.com/actions/python-versions/releases/download/3.14.0-18313368925/python-3.14.0-linux-22.04-${{ matrix.arch }}-freethreaded.tar.gz"
+          tar -xzf python.tar.gz
+          echo "$PWD/python-3.14.0-linux-22.04-${{ matrix.arch }}-freethreaded/bin" >> $GITHUB_PATH
+        elif [ "${{ matrix.platform }}" = "win32" ]; then
+          curl -L -o python.zip "https://github.com/actions/python-versions/releases/download/3.14.0-18313368925/python-3.14.0-win32-${{ matrix.arch }}-freethreaded.zip"
+          Expand-Archive python.zip -DestinationPath .
+          echo "$PWD/python-3.14.0-win32-${{ matrix.arch }}-freethreaded" >> $env:GITHUB_PATH
+        elif [ "${{ matrix.platform }}" = "darwin" ]; then
+          curl -L -o python.tar.gz "https://github.com/actions/python-versions/releases/download/3.14.0-18313368925/python-3.14.0-darwin-${{ matrix.arch }}-freethreaded.tar.gz"
+          tar -xzf python.tar.gz
+          echo "$PWD/python-3.14.0-darwin-${{ matrix.arch }}-freethreaded/bin" >> $GITHUB_PATH
+        fi
+
+    - name: Install uv
+      uses: astral-sh/setup-uv@v6
+      with:
+        enable-cache: true
+        cache-dependency-glob: |
+          requirements*.txt
+          requirements-dev.in
+          pyproject.toml
+
+    - name: Install dependencies
+      run: |
+        uv pip install --system -e .
+        uv pip install --system pytest pytest-xdist pytest-cov
+
+    - name: Create coverage directory
+      run: mkdir -p coverage/reports
+
+    - name: Run tests with freethreaded Python
+      run: |
+        pytest --cov=json2xml --cov-report=xml:coverage/reports/coverage.xml --cov-report=term -xvs tests -n auto
+      env:
+        PYTHONPATH: ${{ github.workspace }}
+        PYTHON_FREETHREADED: 1
+
+    - name: Upload coverage to Codecov
+      uses: codecov/codecov-action@v5
+      if: success()
+      with:
+        directory: ./coverage/reports/
+        env_vars: OS,PYTHON
+        fail_ci_if_error: false  # Don't fail CI if codecov upload fails
+        files: ./coverage/reports/coverage.xml
+        flags: freethreaded
+        token: ${{ secrets.CODECOV_TOKEN }}
+        name: codecov-freethreaded
+        verbose: true
+      env:
+        OS: ${{ matrix.os }}
+        PYTHON: ${{ matrix.python-version }}-freethreaded
+