ci: fix aarch64 cross-compilation by specifying Python interpreters

The cross-compilation Docker container (manylinux2014-cross:aarch64)
doesn't have Python interpreters auto-discoverable like native builds.
Maturin failed with "Couldn't find any python interpreters".

Fix: explicitly specify Python 3.9-3.13 via -i flags for the aarch64
cross-compilation target.

Author: 27Bslash6

.github/workflows/release-please.yml

@@ -42,27 +42,45 @@ jobs:
     strategy:
       matrix:
         include:
+          # Native builds - maturin auto-discovers Python interpreters
           - os: ubuntu-latest
             target: x86_64-unknown-linux-gnu
-          - os: ubuntu-latest
-            target: aarch64-unknown-linux-gnu
           - os: macos-latest
             target: x86_64-apple-darwin
           - os: macos-latest
             target: aarch64-apple-darwin
           - os: windows-latest
             target: x86_64-pc-windows-msvc
+          # Cross-compilation - must specify Python versions explicitly
+          # (cross containers don't have discoverable Python interpreters)
+          - os: ubuntu-latest
+            target: aarch64-unknown-linux-gnu
+            interpreter: -i python3.9 -i python3.10 -i python3.11 -i python3.12 -i python3.13
     runs-on: ${{ matrix.os }}
     steps:
       - uses: actions/checkout@v4
         with:
           ref: ${{ needs.release-please.outputs.tag_name }}
 
+      # Python setup required for native builds (macOS/Windows) to discover interpreters
+      # Linux uses Docker containers which have Python pre-installed
+      - name: Set up Python
+        if: matrix.os != 'ubuntu-latest'
+        uses: actions/setup-python@v5
+        with:
+          python-version: |
+            3.9
+            3.10
+            3.11
+            3.12
+            3.13
+
       - uses: PyO3/maturin-action@v1
         with:
           target: ${{ matrix.target }}
-          args: --release --out dist
+          args: --release --out dist ${{ matrix.interpreter }}
           manylinux: auto
+          rust-toolchain: stable
 
       - uses: actions/upload-artifact@v4
         with:
@@ -83,6 +101,7 @@ jobs:
         with:
           command: sdist
           args: --out dist
+          rust-toolchain: stable
 
       - uses: actions/upload-artifact@v4
         with: