chore: Ignore lerna.json for prettier (#19288)

This caused issues in releases where the file got modified somewhere in
the lerna pipeline which then failed our prettier job.

Author: chargome

.prettierignore

@@ -4,4 +4,6 @@ dev-packages/browser-integration-tests/fixtures
 **/test.ts-snapshots/**
 
 /.nx/cache
-/.nx/workspace-data
+/.nx/workspace-data
+
+lerna.json