test: fix coverage

lib/datasource/git-tags/index.js

@@ -6,6 +6,7 @@ const cacheMinutes = 10;
 async function getPkgReleases({ lookupName }) {
   try {
     const cachedResult = await renovateCache.get(cacheNamespace, lookupName);
+    // istanbul ignore if
     if (cachedResult) return cachedResult;
 
     const info = await getRemoteInfo({