logs: reduce release notes logging

lib/workers/pr/release-notes.js

@@ -15,7 +15,7 @@ module.exports = {
 };
 
 async function getReleaseList(repository) {
-  logger.debug('getReleaseList()');
+  logger.trace('getReleaseList()');
   try {
     const res = await ghGot(`repos/${repository}/releases?per_page=100`);
     return res.body.map(release => ({
@@ -58,7 +58,7 @@ function massageBody(input, githubBaseURL) {
 }
 
 async function getReleaseNotes(repository, version, githubBaseURL) {
-  logger.debug(`getReleaseNotes(${repository}, ${version})`);
+  logger.trace(`getReleaseNotes(${repository}, ${version})`);
   const releaseList = await getReleaseList(repository);
   let releaseNotes;
   releaseList.forEach(release => {