Bump GHA runners (#412)

Author: nmattia

.github/workflows/test.yml

@@ -8,7 +8,7 @@ jobs:
   tests:
     strategy:
       matrix:
-        os: [ubuntu-20.04, macos-12]
+        os: [ubuntu-24.04, macos-15]
     runs-on: ${{ matrix.os }}
     steps:
     - uses: actions/checkout@v4