ci: replace validate-commit-msg with commitlint on Travis (#3523)

Former is [deprecated](https://www.npmjs.com/package/validate-commit-msg) in favor of later. Karma already uses commitlint + husky to do commit validation locally. Added a dedicated package to simplify Travis integration as described in the commitlint [documentation](https://commitlint.js.org/#/guides-ci-setup).

As a bonus it provides a good error message when Travis fails because of the bad commit message ([example](https://travis-ci.org/github/karma-runner/karma/jobs/688059354#L92)).

.travis.yml

@@ -21,11 +21,7 @@ jobs:
     - node_js: "14"
       script:
         - npm run init
-        - echo "TRAVIS_COMMIT $TRAVIS_COMMIT"
-        - echo "TRAVIS_PULL_REQUEST_SHA $TRAVIS_PULL_REQUEST_SHA"
-        - COMMIT_TO_VALIDATE=${TRAVIS_PULL_REQUEST_SHA:-$TRAVIS_COMMIT}
-        - echo "COMMIT_TO_VALIDATE $COMMIT_TO_VALIDATE"
-        - ./scripts/validate-commit-msg.sh $COMMIT_TO_VALIDATE
+        - commitlint-travis
         - npm run lint
         - npm run build
         - npm run test:unit

gruntfile.js

@@ -7,8 +7,7 @@ module.exports = function (grunt) {
       client: ['client/**/*.js'],
       common: ['common/**/*.js'],
       context: ['context/**/*.js'],
-      grunt: ['grunt.js', 'tasks/*.js'],
-      scripts: ['scripts/init-dev-env.js']
+      grunt: ['grunt.js', 'tasks/*.js']
     },
     browserify: {
       client: {

package.json

@@ -418,6 +418,7 @@
   "devDependencies": {
     "@commitlint/cli": "^8.3.4",
     "@commitlint/config-conventional": "^8.3.4",
+    "@commitlint/travis-cli": "^8.3.5",
     "@semantic-release/changelog": "^3.0.6",
     "@semantic-release/git": "^7.0.18",
     "browserify": "^16.2.3",
@@ -466,7 +467,6 @@
     "sinon-chai": "^3.0.0",
     "supertest": "^4.0.2",
     "timer-shim": "^0.3.0",
-    "validate-commit-msg": "^2.11.1",
     "which": "^1.3.1"
   },
   "main": "./lib/index",