fix: update condition for minting identity token in Gemini review workflow

- Changed the condition for minting the identity token from checking GOOGLE_API_KEY to APP_ID.

Author: ssdeanx

.github/workflows/gemini-review.yml

@@ -29,7 +29,7 @@ jobs:
       - name: 'Mint identity token'
         id: 'mint_identity_token'
         if: |-
-          ${{ vars.GOOGLE_API_KEY }}
+          ${{ vars.APP_ID }}
         uses: 'actions/create-github-app-token@a8d616148505b5069dccd32f177bb87d7f39123b' # ratchet:actions/create-github-app-token@v2
         with:
           app-id: '${{ vars.AgentStack }}'