Correct flaky test for parseUses

Fix a flaky test for the `parseUses` function which could fail if the
randomly generated `ref` value contained an at sign. This would result
in a constructed `uses:` value with multiple at signs, which is not
valid (and would thus error unexpectedly).

This is a followup to 8588dff

internal/gha/parse_test.go

@@ -183,7 +183,7 @@ func TestParseUses(t *testing.T) {
 				repo = fmt.Sprintf("%s/%s", repo, path)
 			}
 
-			if strings.ContainsRune(repo, '@') {
+			if strings.ContainsRune(repo, '@') || strings.ContainsRune(ref, '@') {
 				return true
 			}