[ci] Bump google-github-actions/setup-gcloud from v2 to v3.0.1

Pick up changes to the Node 24 runtime, as Node.js 20 actions are
currently deprecated and will mean this action is soon end-of-life.

There are no breaking changes across this major version bump for our use
case, so we move to using the latest major release.

This action does not support immutable releases, so we pin the specific
hash of the v3.0.1 release for security.

Signed-off-by: Alex Jones <alex.jones@lowrisc.org>
(cherry picked from commit f12bf17)

Author: AlexJones0

.github/actions/prepare-env/action.yml

@@ -112,7 +112,7 @@ runs:
         echo "GOOGLE_GHA_CREDS_PATH=$TARGET" >> $GITHUB_ENV
       shell: bash
 
-    - uses: google-github-actions/setup-gcloud@v2
+    - uses: google-github-actions/setup-gcloud@aa5489c8933f4cc7a4f7d45035b3b1440c9c10db  # v3.0.1
       if: github.event_name != 'pull_request' && inputs.service_account_json != ''
 
     - name: Configure ~/.bazelrc