fix: drop packageFile.fileName support

No longer massages packageFile.fileName -> packageFile.packageFile

BREAKING CHANGE: “fileName” notation no longer supported

lib/workers/repository/upgrades.js

@@ -63,11 +63,6 @@ function getPackageFileConfig(repoConfig, index) {
   let packageFile = repoConfig.packageFiles[index];
   if (typeof packageFile === 'string') {
     packageFile = { packageFile };
-  } else if (packageFile.fileName) {
-    // Retained deprecated 'fileName' for backwards compatibility
-    // TODO: Remove in renovate 9
-    packageFile.packageFile = packageFile.fileName;
-    delete packageFile.fileName;
   }
   const packageFileConfig = Object.assign({}, repoConfig, packageFile);
   repoConfig.logger.trace({ config: repoConfig }, 'repoConfig');

test/workers/repository/upgrades.spec.js

@@ -35,7 +35,7 @@ describe('workers/repository/upgrades', () => {
           packageFile: 'backend/package.json',
         },
         {
-          fileName: 'frontend/package.json',
+          packageFile: 'frontend/package.json',
         },
       ];
       packageFileWorker.findUpgrades.mockReturnValueOnce(['a']);