mach: recreate .venv when .python-version changes (#34712)

The new images published in servo/ci-runners#12 should have `uv`
installed already and the initial build of servo triggered during the
base image construction will force the installation of the Python
version mentioned at the time of the image construction (3.12). When
.python-version changes, we can no longer use the .venv baked into the
image and must recreate the it to avoid activating the environment.

Signed-off-by: Mukilan Thiyagarajan <mukilan@igalia.com>

.github/workflows/android.yml

@@ -57,7 +57,7 @@ jobs:
       - name: Setup Python
         uses: ./.github/actions/setup-python
       - name: Bootstrap dependencies
-        run: sudo apt update && python3 ./mach bootstrap --skip-lints
+        run: sudo apt update && ./mach bootstrap --skip-lints
       - name: Set up JDK 17
         uses: actions/setup-java@v4
         with:
@@ -95,7 +95,7 @@ jobs:
           APK_SIGNING_KEY_ALIAS: ${{ secrets.APK_SIGNING_KEY_ALIAS }}
           APK_SIGNING_KEY_PASS: ${{ secrets.APK_SIGNING_KEY_PASS }}
         run: |
-          python3 ./mach build --use-crown --locked --target ${{ matrix.target }} --${{ inputs.profile }}
+          ./mach build --use-crown --locked --target ${{ matrix.target }} --${{ inputs.profile }}
           cp -r target/cargo-timings target/cargo-timings-android-${{ matrix.target }}
       # TODO: This is disabled since APK crashes during startup.
       # See https://github.com/servo/servo/issues/31134
@@ -110,7 +110,7 @@ jobs:
       - name: Upload nightly
         if: ${{ inputs.upload && contains(matrix.target, 'aarch64') }}
         run: |
-          python3 ./mach upload-nightly android \
+          ./mach upload-nightly android \
             --secret-from-environment \
             --github-release-id ${{ inputs.github-release-id }}
         env: