github: update runners to -latest

macos-10.15 has long been unavailable. Future-proof it by using -latest for everything.

.github/workflows/publish.yml

@@ -16,7 +16,7 @@ jobs:
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
-        os: [ubuntu-20.04, windows-2019, macos-10.15]
+        os: [ubuntu-latest, windows-latest, macos-latest]
 
     steps:
       - uses: actions/checkout@v3
@@ -41,7 +41,7 @@ jobs:
 
   build_sdist:
     name: Build source distribution
-    runs-on: ubuntu-22.04
+    runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v3
         with:
@@ -56,7 +56,7 @@ jobs:
 
   upload_pypi:
     needs: [build_wheels, build_sdist]
-    runs-on: ubuntu-22.04
+    runs-on: ubuntu-latest
     # upload to PyPI on every tag
     if: github.event_name == 'push' && github.ref_type == 'tag'
     steps: