polish(auth): Git ignore test/support/.tmp folder

Author: dschom

.gitignore

@@ -115,6 +115,7 @@ packages/fxa-auth-server/fxa-content-server-l10n
 packages/fxa-auth-server/lib/senders/emails/css
 packages/fxa-auth-server/public/locales
 packages/fxa-auth-server/vendor
+packages/fxa-auth-server/test/support/.tmp
 
 # fxa-content-server
 packages/fxa-content-server/pids