chore: add debugging to semantic commit detection

lib/workers/repository/updates/semantic.js

 const conventionalCommitsDetector = require('conventional-commits-detector');
 
 async function detectSemanticCommits(config) {
+  logger.debug('detectSemanticCommits()');
+  logger.trace({ config });
   if (config.semanticCommits !== null) {
+    logger.debug(
+      { semanticCommits: config.semanticCommits },
+      `semanticCommits already defined`
+    );
     return config.semanticCommits;
   }
   const commitMessages = await platform.getCommitMessages();