chore(deps): update dependency @types/js-yaml to v3.12.0 (#400)

Author: renovate[bot]

packages/graphqlgen/package.json

@@ -57,7 +57,7 @@
     "@types/camelcase": "4.1.0",
     "@types/graphql": "14.0.5",
     "@types/jest": "23.3.12",
-    "@types/js-yaml": "3.11.4",
+    "@types/js-yaml": "3.12.0",
     "@types/mkdirp": "0.5.2",
     "@types/node": "10.12.18",
     "@types/prettier": "1.15.2",