Disable fail-fast in C++ compatibility matrix

Allow both Ubuntu and macOS jobs to complete even if one fails
to collect artifacts and diffs from both platforms

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <[email protected]>

.github/workflows/spine-cpp-compatibility.yml

@@ -7,6 +7,7 @@ on:
 jobs:
   test-cpp-java-compatibility:
     strategy:
+      fail-fast: false
       matrix:
         os: [ubuntu-latest, macos-latest]
     runs-on: ${{ matrix.os }}