run the check for go generated files on Github Actions instead of Travis

.github/workflows/go-generate.sh

@@ -0,0 +1,21 @@
+#!/usr/bin/env bash
+
+set -e
+
+find . -type f -name "*.go" -exec shasum {} \; > checksums_before.txt
+# delete all go-generated files generated (that adhere to the comment convention)
+grep --include \*.go --exclude-dir quictrace/ -lrIZ "^// Code generated .* DO NOT EDIT\.$" . | xargs --null rm
+# delete all files generated by Genny
+grep --include \*.go -lrIZ "This file was automatically generated by genny." . | xargs --null rm
+# first generate Genny files to make the code compile
+grep --include \*.go -lrI "//go:generate genny" | xargs -L 1 go generate
+# now generate everything
+go generate ./...
+find . -type f -name "*.go" -exec shasum {} \; > checksums_after.txt
+DIFF=$(diff checksums_before.txt checksums_after.txt) || true
+echo "$DIFF"
+if [ -n "$DIFF" ]; then
+  exit 1
+else
+  echo "All generated files match."
+fi