Add ubuntu 20.04

Author: Bill-hbrhbr

.github/workflows/unit-tests.yaml

@@ -22,6 +22,7 @@ jobs:
       matrix:
         os:
           - "macos-latest"
+          - "ubuntu-20.04"
           - "ubuntu-22.04"
           - "ubuntu-24.04"
     runs-on: "${{matrix.os}}"