fix(changelog): Revert platform dispatch changes (#23048)

lib/workers/repository/update/pr/changelog/index.ts

@@ -26,23 +26,29 @@ export async function getChangeLogJSON(
       `Fetching changelog: ${sourceUrl} (${currentVersion} -> ${newVersion})`
     );
 
+    let res: ChangeLogResult | null = null;
+
     const platform = detectPlatform(sourceUrl);
 
-    if (platform === 'github') {
-      return await sourceGithub.getChangeLogJSON(config);
-    }
+    switch (platform) {
+      case 'gitlab':
+        res = await sourceGitlab.getChangeLogJSON(config);
+        break;
+      case 'github':
+        res = await sourceGithub.getChangeLogJSON(config);
+        break;
 
-    if (platform === 'gitlab') {
-      return await sourceGitlab.getChangeLogJSON(config);
+      default:
+        logger.info(
+          { sourceUrl, hostType: platform },
+          'Unknown platform, skipping changelog fetching.'
+        );
+        break;
     }
 
-    logger.info(
-      { sourceUrl, hostType: platform },
-      'Unknown platform, skipping changelog fetching.'
-    );
+    return res;
   } catch (err) /* istanbul ignore next */ {
     logger.error({ config, err }, 'getChangeLogJSON error');
+    return null;
   }
-
-  return null;
 }