[3.13] GH-119292: Add job to JIT CI to build and test with --disable-gil (GH-119314)

(cherry picked from commit c4722cd)
Co-authored-by: Savannah Ostrowski <savannahostrowski@gmail.com>
Co-authored-by: Hugo van Kemenade <1324225+hugovk@users.noreply.github.com>

Author: miss-islington

Diff for: .github/workflows/jit.yml

@@ -150,3 +150,21 @@ jobs:
             ./configure --enable-experimental-jit ${{ matrix.debug && '--with-pydebug' || '--enable-optimizations ' }} --build=x86_64-linux-gnu --host="$HOST" --with-build-python=../build/bin/python3 --with-pkg-config=no ac_cv_buggy_getaddrinfo=no ac_cv_file__dev_ptc=no ac_cv_file__dev_ptmx=yes
           make all --jobs 4
           ./python -m test --ignorefile=Tools/jit/ignore-tests-emulated-linux.txt --multiprocess 0 --timeout 4500 --verbose2 --verbose3
+
+  jit-with-disabled-gil:
+    name: Free-Threaded (Debug)
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-python@v5
+        with:
+          python-version: '3.11'
+      - name: Build with JIT enabled and GIL disabled
+        run: |
+          sudo bash -c "$(wget -O - https://apt.llvm.org/llvm.sh)" ./llvm.sh 18
+          export PATH="$(llvm-config-18 --bindir):$PATH"
+          ./configure --enable-experimental-jit --with-pydebug --disable-gil
+          make all --jobs 4
+      - name: Run tests
+        run: |
+          ./python -m test --multiprocess 0 --timeout 4500 --verbose2 --verbose3