build: use GraphQL URL from env in gql-codegen (#2749)

Co-authored-by: Andrew Bastin <andrewbastin.k@gmail.com>

.github/workflows/tests.yml

@@ -19,6 +19,8 @@ jobs:
       - uses: actions/setup-node@v2
       - name: Setup and run pnpm install
         uses: pnpm/action-setup@v2.2.2
+        env:
+          VITE_BACKEND_GQL_URL: ${{ secrets.BACKEND_GQL_URL }}
         with:
           version: 7
           run_install: true