bug: cel tests are always run on a single version of Kubernetes (envo…

…yproxy#3584)

The cel test invocation was using the wrong verison of Kubernetes every
time it was being run.

Signed-off-by: Lior Okman <lior.okman@sap.com>

tools/make/golang.mk

@@ -66,7 +66,7 @@ go.test.cel: manifests $(tools/setup-envtest) # Run the CEL validation tests
 	@for ver in $(ENVTEST_K8S_VERSIONS); do \
   		echo "Run CEL Validation on k8s $$ver"; \
         go clean -testcache; \
-        KUBEBUILDER_ASSETS="$(shell $(tools/setup-envtest) use $$ver -p path)" \
+        KUBEBUILDER_ASSETS="$$($(tools/setup-envtest) use $$ver -p path)" \
          go test ./test/cel-validation --tags celvalidation -race; \
     done