Update the cirrus key jul-31-2023 (flutter#4618)

Update the cirrus key.

*List which issues are fixed by this PR. You must list at least one issue.*

*If you had to change anything in the [flutter/tests] repo, include a link to the migration guide as per the [breaking change policy].*

.cirrus.yml

@@ -1,4 +1,4 @@
-gcp_credentials: ENCRYPTED[!9c8e92e8da192ce2a51b7d4ed9948c4250d0bae3660193d9b901196c9692abbebe784d4a32e9f38b328571d65f6e7aed!]
+gcp_credentials: ENCRYPTED[!9409b709ab4de7293a70606cca13eaf42e9cbc704e8a6b4e3d2b09484cf997cbd2334e1eeafe23626ad07a726106df90!]
 
 # Run on PRs and main branch post submit only. Don't run tests when tagging.
 only_if: $CIRRUS_TAG == '' && ($CIRRUS_PR != '' || $CIRRUS_BRANCH == 'main')