Generate go-licenses during tidy again (#21108)

We can not have the `frontend` target depend on golang because of they
way drone is set up. Move the `go-licenses` generation back into `tidy`
where it will now also be checked for consistency during `tidy-check`.

(I assume all `main` branch builds should currently fail [like
this](https://drone.gitea.io/go-gitea/gitea/60244/1/11)).

The reasony why it shouldn't be treated the same as for example `go
generate` is because output files are checked in. tidy is imho the
optimal target to run this after.

Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>

build/generate-go-licenses.go

@@ -54,9 +54,17 @@ func main() {
 		}
 
 		path := strings.Replace(path, base+string(os.PathSeparator), "", 1)
+		name := filepath.Dir(path)
+
+		// There might be a bug somewhere in go-licenses that sometimes interprets the
+		// root package as "." and sometimes as "code.gitea.io/gitea". Workaround by
+		// removing both of them for the sake of stable output.
+		if name == "." || name == "code.gitea.io/gitea" {
+			continue
+		}
 
 		entries = append(entries, LicenseEntry{
-			Name: filepath.Dir(path),
+			Name: name,
 			Path: path,
 			LicenseText: string(licenseText),
 		})