Fix incorrect gotestfmt output

Use our fork until

    GoTestTools/gotestfmt#62

has been merged by upstream.

Author: adombeck

gh-actions/go/gotestfmt/action.yaml

@@ -13,7 +13,7 @@ runs:
       run: |
         # Install gotestfmt
         set -eu
-        TOOL=github.com/gotesttools/gotestfmt/v2/cmd/gotestfmt
+        TOOL=github.com/ubuntu/gotestfmt/v2/cmd/gotestfmt
         VERSION=$(go mod edit --json | jq -r ".Require[] | select(.Path==\"${TOOL}\") | .Version" || true)
 
         if [ -z "${VERSION}" ]; then