fix: upgrade test pnpm install from commit (#4600)

.github/workflows/upgrade-test.yml

@@ -190,6 +190,7 @@ jobs:
           git checkout ${{ github.sha }}
           git rev-parse HEAD
           cd bouncer
+          pnpm install
           ./commands/upgrade_network.ts prebuilt \
             --runtime ./../main-runtime/state_chain_runtime.compact.compressed.wasm \
             --bins ./../upgrade-to-bins \