Remove go version supported in tests

Author: andywhittle

.github/workflows/go.yml

@@ -10,7 +10,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        go: [ '1.21', '1.22', '1.23', '1.24' ]
+        go: [ '1.23', '1.24' ]
     name: Go ${{ matrix.go }} tests
     steps:
     - uses: actions/checkout@v2