[CI] Forcing Ubuntu 22.04 for Linux builds

- Recent clang versions, which the 24.04 uses, fail to compile sol2's current code
  - This is an issue that's been known for a while and a fix has been done on their side, but no new version has been released yet

.github/workflows/RaZ.yml

@@ -12,7 +12,7 @@ jobs:
       ${{ !matrix.use_audio && ', no audio' || '' }}\
       ${{ !matrix.use_lua && ', no Lua' || '' }}\
       ${{ !matrix.use_window && ', no window' || '' }})"
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-22.04
 
     strategy:
       fail-fast: false