Add fail if sha256sum does not present

Without this, there is an incomprehensible error if sha256sum does not present.

This fixes by determining the reason for error sha256sum not present

Makefile

@@ -9,6 +9,7 @@ $(HACKDIR):
 	mkdir -p $(HACKDIR)
 
 bootstrap-tools: $(HACKDIR)
+	if ! command -v sha256sum &> /dev/null; then echo "sha256sum could not be found"; exit 1; fi
 	command -v $(HACKDIR)/goreleaser || VERSION=v2.5.0 TMPDIR=$(HACKDIR) bash hack/goreleaser-install.sh
 	command -v staticcheck || go install honnef.co/go/tools/cmd/staticcheck@latest
 	chmod +x $(HACKDIR)/goreleaser