[makefile] Support for sed on Darwin (kubernetes-sigs#1920)

* [makefile] Support for sed on Darwin

* [makefile] Update makefile to choose sed via `command -v`

Makefile

@@ -84,7 +84,13 @@ SHELL = /usr/bin/env bash -o pipefail
 
 # Setting SED allows macos users to install GNU sed and use the latter
 # instead of the default BSD sed.
-SED ?= /usr/bin/sed
+SED ?= $(shell command -v sed)
+ifeq ($(shell command -v gsed 2>/dev/null),)
+    SED = $(shell command -v sed)
+endif
+ifeq ($(shell ${SED} --version 2>&1 | grep -q GNU; echo $$?),1)
+    $(error !!! GNU sed is required. If on OS X, use 'brew install gnu-sed'.)
+endif
 
 version_pkg = sigs.k8s.io/kueue/pkg/version
 LD_FLAGS += -X '$(version_pkg).GitVersion=$(GIT_TAG)'
@@ -312,7 +318,7 @@ artifacts: kustomize yq helm
 
 .PHONY: prepare-release-branch
 prepare-release-branch: yq kustomize
-	sed -r 's/v[0-9]+\.[0-9]+\.[0-9]+/$(RELEASE_VERSION)/g' -i README.md -i site/hugo.toml
+	$(SED) -r 's/v[0-9]+\.[0-9]+\.[0-9]+/$(RELEASE_VERSION)/g' -i README.md -i site/hugo.toml
 	$(YQ) e '.appVersion = "$(RELEASE_VERSION)"' -i charts/kueue/Chart.yaml
 	@$(call clean-manifests)