build: configure user name/email for git (#1886)

Towards #1840

Author: chingor13

infra/prod/stage-release.yaml

@@ -23,9 +23,25 @@ steps:
     args:
       - 'clone'
       - $_FULL_REPOSITORY
+  - name: gcr.io/cloud-builders/git
+    id: configure-language-repo-name
+    waitFor: ['clone-language-repo']
+    dir: /workspace/$_REPOSITORY
+    args:
+      - 'config'
+      - 'user.name'
+      - 'Cloud SDK Librarian'
+  - name: gcr.io/cloud-builders/git
+    id: configure-language-repo-email
+    waitFor: ['configure-language-repo-name']
+    dir: /workspace/$_REPOSITORY
+    args:
+      - 'config'
+      - 'user.email'
+      - 'cloud-sdk-librarian-robot@google.com'
   - name: 'us-central1-docker.pkg.dev/cloud-sdk-librarian-prod/images-prod/librarian'
     id: stage-release
-    waitFor: ['clone-language-repo']
+    waitFor: ['configure-language-repo-email']
     dir: tmp
     args:
       - 'release'