Update gitignore for yarn files (#512)

Author: kevinwcyu

.gitignore

@@ -16,4 +16,13 @@ provisioning/
 /playwright-report/
 /blob-report/
 /playwright/.cache/
-/playwright/.auth/
+/playwright/.auth/
+
+# yarn
+.pnp.*
+.yarn/*
+!.yarn/patches
+!.yarn/plugins
+!.yarn/releases
+!.yarn/sdks
+!.yarn/versions