Use conditional assignment for BRANCH

Signed-off-by: Martin Schuppert <[email protected]>

Author: stuggi

Makefile

@@ -355,7 +355,7 @@ run-with-webhook: manifests generate fmt vet ## Run a controller from your host.
 	/bin/bash hack/run_with_local_webhook.sh
 
 CRD_SCHEMA_CHECKER_VERSION ?= release-4.16
-BRANCH=main
+BRANCH ?= main
 
 PHONY: crd-schema-check
 crd-schema-check: manifests