make matrix repetitive

Author: mattip

Diff for: .github/workflows/nanobind.yml

@@ -24,8 +24,8 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        os: ['ubuntu-latest', 'windows-2022', 'macos-latest']
-        python: ['3.8', '3.9', '3.10', '3.11', '3.12', '3.13.0-alpha.3', 'pypy3.9-v7.3.15', 'pypy3.10-v7.3.15']
+        os: ['ubuntu-latest', 'ubuntu-latest', 'ubuntu-latest', 'ubuntu-latest']
+        python: ['pypy3.9-v7.3.15', 'pypy3.10-v7.3.15', 'pypy3.9-v7.3.15', 'pypy3.10-v7.3.15', 'pypy3.9-v7.3.15', 'pypy3.10-v7.3.15', 'pypy3.9-v7.3.15', 'pypy3.10-v7.3.15']
 
     name: "Python ${{ matrix.python }} / ${{ matrix.os }}"
     runs-on: ${{ matrix.os }}