fix(deps): update dependency pinyin to v4

Author: renovate[bot]

package.json

@@ -50,7 +50,7 @@
     "oas-resolver": "^2.5.6",
     "oas-schema-walker": "^1.1.5",
     "openapi-sampler": "^1.4.0",
-    "pinyin": "^3.1.0",
+    "pinyin": "^4.0.0",
     "reftools": "^1.1.9",
     "swagger2openapi": "^7.0.8",
     "urijs": "^1.19.11",