ci: update GitHub Actions workflow and testing configurations

- Remove support for Go versions 1.20 and 1.21 in the GitHub Actions workflow

Signed-off-by: appleboy <[email protected]>

Author: appleboy

.github/workflows/go.yml

@@ -23,7 +23,7 @@ jobs:
     strategy:
       matrix:
         os: [ubuntu-latest]
-        go: ["1.20", 1.21, 1.22, 1.23]
+        go: [1.22, 1.23]
         include:
           - os: ubuntu-latest
             go-build: ~/.cache/go-build