Update CI images.

Author: larsbrinkhoff

.github/workflows/build.yml

@@ -11,7 +11,7 @@ jobs:
     runs-on: ${{matrix.os}}
     strategy:
       matrix:
-        os: [ubuntu-18.04, ubuntu-20.04, macos-10.15]
+        os: [ubuntu-22.04, ubuntu-24.04, macos-14, macos-15]
     steps:
       - uses: actions/checkout@v2
       - name: Install dependencies