Updated Github Actions checkout and cache versions

Author: andrew@technative.eu

.github/workflows/tflint.yaml

@@ -13,10 +13,10 @@ jobs:
         os: [ubuntu-latest]
 
     steps:
-    - uses: actions/checkout@v2
+    - uses: actions/checkout@v3
       name: Checkout source code
 
-    - uses: actions/cache@v2
+    - uses: actions/cache@v3
       name: Cache plugin dir
       with:
         path: ~/.tflint.d/plugins