Fix dependency incompatibilities

lib/testing-utils.js

@@ -178,8 +178,10 @@ function mockLanguagesInRepo(languages) {
     });
     // eslint-disable-next-line @typescript-eslint/no-unsafe-argument
     mockClient.returns({
-        repos: {
-            listLanguages,
+        rest: {
+            repos: {
+                listLanguages,
+            },
         },
     });
     return listLanguages;