update version check

Makefile

@@ -254,7 +254,7 @@ require-app: guard-APP
 
 .PHONY: require-version
 require-version: guard-VERSION
-	@if ! [[ "$$VERSION" =~ ^[0-9]+\.[0-9]+\.[0-9]+(-.+)?$$ ]]; then \
+	@if ! echo "$$VERSION" | grep -Eq "^[0-9]+\.[0-9]+\.[0-9]+(-.+)?$$"; then \
 		echo "VERSION must be a semantic version like '1.2.10' or '1.2.10-foo"; \
 		exit 1; \
 	fi