refactor(changelog): cacheKey from manager/depName

lib/workers/pr/changelog/source-github.js

@@ -44,6 +44,7 @@ async function getChangeLogJSON({
   repositoryUrl,
   releases,
   depName,
+  manager,
 }) {
   if (repositoryUrl === 'https://github.com/DefinitelyTyped/DefinitelyTyped') {
     logger.debug('No release notes for @types');
@@ -101,7 +102,7 @@ async function getChangeLogJSON({
 
   const cacheNamespace = 'changelog-github-release';
   function getCacheKey(prev, next) {
-    return `${repository}:${prev}:${next}`;
+    return `${manager}:${depName}:${prev}:${next}`;
   }
 
   const changelogReleases = [];