actions: remove Ubuntu 20.04, add 24.04

Author: miek

.github/workflows/build.yml

@@ -17,7 +17,7 @@ jobs:
   build:
     strategy:
       matrix:
-        os: ['macos-latest', 'ubuntu-22.04', 'ubuntu-20.04']
+        os: ['macos-latest', 'ubuntu-24.04', 'ubuntu-22.04']
     runs-on: ${{ matrix.os }}
 
     steps: