chore: support prettier v2 (#89)

Author: JounQin

Diff for: package.json

@@ -66,6 +66,6 @@
     "vue-template-es2015-compiler": "^1.9.0"
   },
   "optionalDependencies": {
-    "prettier": "^1.18.2"
+    "prettier": "^1.18.2 || ^2.0.0"
   }
 }

Diff for: yarn.lock

@@ -4040,7 +4040,7 @@ prelude-ls@~1.1.2:
   resolved "https://registry.yarnpkg.com/prelude-ls/-/prelude-ls-1.1.2.tgz#21932a549f5e52ffd9a827f570e04be62a97da54"
   integrity sha1-IZMqVJ9eUv/ZqCf1cOBL5iqX2lQ=
 
-prettier@^1.18.2:
+"prettier@^1.18.2 || ^2.0.0":
   version "1.19.1"
   resolved "https://registry.yarnpkg.com/prettier/-/prettier-1.19.1.tgz#f7d7f5ff8a9cd872a7be4ca142095956a60797cb"
   integrity sha512-s7PoyDv/II1ObgQunCbB9PdLmUcBZcnWOcxDh7O0N/UwDEsHyqkW+Qh28jW+mVuCdx7gLB0BotYI1Y6uI9iyew==