.github/workflows/google-fonts.yml: ensure commits are signed

Author: bevanjkay

.github/workflows/google-fonts.yml

@@ -96,6 +96,10 @@ jobs:
         with:
           token: ${{ secrets.HOMEBREW_GITHUB_PUBLIC_REPO_TOKEN }}
           branch: "auto-${{ matrix.mode }}-google-fonts"
+          GIT_COMMITTER_NAME: ${{ steps.git-user-config.outputs.name }}
+          GIT_COMMITTER_EMAIL: ${{ steps.git-user-config.outputs.email }}
+          HOMEBREW_GPG_PASSPHRASE: ${{ secrets.BREWTESTBOT_GPG_SIGNING_SUBKEY_PASSPHRASE }}
+
 
       - name: Create pull request with updated files
         if: env.changes == 'true'