enable experimental for conformance test

Author: sarthyparty

.github/workflows/conformance.yml

@@ -75,6 +75,7 @@ jobs:
         run: |
           ngf_prefix=ghcr.io/nginxinc/nginx-gateway-fabric
           ngf_tag=${{ steps.ngf-meta.outputs.version }}
+          if [ ${{ inputs.enable-experimental }} == "true" ]; then export ENABLE_EXPERIMENTAL=true; fi
           make generate-static-deployment PLUS_ENABLED=${{ inputs.image == 'plus' && 'true' || 'false' }} PREFIX=${ngf_prefix} TAG=${ngf_tag}
         working-directory: ./tests