fix: correctly filter pinned versions

lib/datasource/github.js

@@ -31,7 +31,7 @@ async function getDependency(repo, options = {}) {
   if (!versions) {
     return null;
   }
-  versions = versions.filter(isPinnedVersion);
+  versions = versions.filter(version => isPinnedVersion(version));
   if (clean) {
     versions = versions.map(version => version.replace(/^v/, ''));
   }