feat: lint 액션 추가

.github/workflows/lint.yml

@@ -0,0 +1,21 @@
+name: lint
+
+on:
+  pull_request:
+
+jobs:
+  lint:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+
+      - name: Set up JDK 11
+        uses: actions/setup-java@v1
+        with:
+          java-version: 11
+
+      - name: Grant execute permission for gradlew
+        run: chmod +x gradlew
+
+      - name: Test with Spotless
+        run: ./gradlew --info ktlintCheck