Read Go version from go.mod in CI

Author: metalmatze

.github/workflows/go.yaml

@@ -19,7 +19,7 @@ jobs:
       - uses: actions/checkout@v3
       - uses: actions/setup-go@v3
         with:
-          go-version: ${{ env.golang-version }}
+          go-version-file: 'go.mod'
       - run: mkdir -p ui/build && touch ui/build/empty
       - run: make test
       - run: make pyrra