gitlab-ci: Move changelog linting logic to shell script

Allowing it to be easily used locally.

.gitlab-ci.yml

@@ -169,11 +169,7 @@ lint-submods-branch:
   tags:
     - lint
   script:
-    - |
-      grep TBA libraries/*/changelog.md && (
-          echo "Error: Found \"TBA\"s in changelogs."
-          exit 1
-      ) || exit 0
+    - bash .gitlab/linters/check-changelogs.sh
 
 lint-changelogs:
   extends: .lint-changelogs

.gitlab/linters/check-changelogs.sh

+#!/usr/bin/env bash
+
+set -e
+
+COLOR_RED="\e[31m"
+COLOR_GREEN="\e[32m"
+COLOR_NONE="\e[0m"
+
+grep TBA libraries/*/changelog.md && (
+    echo -e "${COLOR_RED}Error: Found \"TBA\"s in changelogs.${COLOR_NONE}"
+    exit 1
+)
+
+echo -e "${COLOR_GREEN}changelogs look okay.${COLOR_NONE}"