try fix helm unittest issues

Author: fealebenpae

Makefile

@@ -298,11 +298,18 @@ test-race: generate fmt vet manifests golang-tests-race
 test: generate fmt vet manifests golang-tests
 
 # helm-tests will run helm chart unit tests
+# some evergreen machines have upgraded to Helm 4, which currently breaks installing the unittest plugin
+# see https://github.com/helm-unittest/helm-unittest/issues/777
 helm-tests:
 	@echo "Running helm chart unit tests..."
 	@if ! helm plugin list | grep -q unittest; then \
 		echo "Installing helm-unittest plugin..."; \
-		helm plugin install https://github.com/helm-unittest/helm-unittest; \
+		HELM_MAJOR_VERSION=$$(helm version --short | grep -oE 'v[0-9]+' | sed 's/v//'); \
+		if [ "$$HELM_MAJOR_VERSION" = "4" ]; then \
+			helm plugin install https://github.com/helm-unittest/helm-unittest --verify=false; \
+		else \
+			helm plugin install https://github.com/helm-unittest/helm-unittest; \
+		fi \
 	fi
 	helm unittest helm_chart --color