add prettier config

Author: toger5

package.json

@@ -23,6 +23,22 @@
     "lint:workflows": "find .github/workflows -type f \\( -iname '*.yaml' -o -iname '*.yml' \\) | xargs -I {} sh -c 'echo \"Linting {}\"; action-validator \"{}\"'",
     "test": "jest"
   },
+  "prettier": {
+    "printWidth": 120,
+    "tabWidth": 2,
+    "quoteProps": "consistent",
+    "trailingComma": "all",
+    "overrides": [
+      {
+        "files": [
+          "src/**/*.ts"
+        ],
+        "options": {
+          "tabWidth": 4
+        }
+      }
+    ]
+  },
   "files": [
     "src",
     "lib",