Update Go version in Actions

Author: cpmech

.github/workflows/go.yml

@@ -19,7 +19,7 @@ jobs:
       - name: Install Go
         uses: actions/setup-go@v2
         with:
-          go-version: ^1.17
+          go-version: ^1.20
       - name: Build all
         run: |
           bash ./all.bash