Test different Ubuntu versions

Author: wolfcw

.github/workflows/make-test.yml

@@ -12,7 +12,7 @@ jobs:
   build:
     strategy:
       matrix:
-        os: [ubuntu-latest, ubuntu-22.04, ubuntu-20.04]
+        os: [ubuntu-latest, ubuntu-22.04]
     runs-on: ${{ matrix.os }}
 
     steps: