Switched to GitHub Actions for lint testing

no issue

.github/workflows/lint.yml

@@ -0,0 +1,17 @@
+name: Lint Check
+on:
+  pull_request:
+  push:
+    branches:
+      - master
+
+jobs:
+  lint:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - uses: actions/setup-node@v1
+        with:
+          node-version: '10'
+      - run: yarn install
+      - run: yarn lint

.travis.yml

@@ -13,19 +13,13 @@ env:
   matrix:
   - DB=sqlite3 NODE_ENV=testing
   - DB=mysql NODE_ENV=testing-mysql
-matrix:
-  include:
-  - node_js: '10'
-    env: TEST_SUITE=lint
 install:
 - yarn
 before_script:
 - if [ $DB == "mysql" ]; then mysql -e 'create database ghost_testing'; fi
 - if [ "$DB" == "sqlite3" ]; then yarn add --force sqlite3; fi
 script: |
-  if [ "$TEST_SUITE" == "lint" ]; then
-    yarn lint
-  elif [[ "$TRAVIS_PULL_REQUEST_BRANCH" =~ ^renovate || "$TRAVIS_EVENT_TYPE" == "cron" ]]; then
+  if [[ "$TRAVIS_PULL_REQUEST_BRANCH" =~ ^renovate || "$TRAVIS_EVENT_TYPE" == "cron" ]]; then
     yarn ci:regression
   else
     yarn ci