benchmarks.yml: use node 18.x with reflex-web@main (#3657)

.github/workflows/benchmarks.yml

@@ -30,7 +30,7 @@ jobs:
         # Show OS combos first in GUI
         os: [ubuntu-latest]
         python-version: ['3.11.4']
-        node-version: ['16.x']
+        node-version: ['18.x']
 
     runs-on: ${{ matrix.os }}
     steps:
@@ -49,7 +49,7 @@ jobs:
         uses: actions/checkout@v4
         with:
           repository: reflex-dev/reflex-web
-          ref: reflex-ci
+          ref: main
           path: reflex-web
 
       - name: Install Requirements for reflex-web