[chore] Makefile - Allow releasing also from release.* branches (#787)

Rationale: https://hub.mattermost.com/private-core/pl/yim6z9us9fdtfrjkdf8i16tczw

Signed-off-by: Akis Maziotis <akis.maziotis@mattermost.com>

Makefile

@@ -52,8 +52,8 @@ RC := $(shell echo $(CURRENT_VERSION) | grep -oE 'rc[0-9]+' | sed 's/rc//')
 # Check if current branch is protected
 define check_protected_branch
 	@current_branch=$$(git rev-parse --abbrev-ref HEAD); \
-	if ! echo "$(PROTECTED_BRANCH)" | grep -wq "$$current_branch"; then \
-		echo "Error: Tagging is only allowed from $(PROTECTED_BRANCH) branch. You are on $$current_branch branch."; \
+	if ! echo "$(PROTECTED_BRANCH)" | grep -wq "$$current_branch" && ! echo "$$current_branch" | grep -q "^release"; then \
+		echo "Error: Tagging is only allowed from $(PROTECTED_BRANCH) or release branches. You are on $$current_branch branch."; \
 		exit 1; \
 	fi
 endef