Bump js-yaml from 3.12.0 to 3.13.1 (networknt#165)

Bumps [js-yaml](https://github.com/nodeca/js-yaml) from 3.12.0 to 3.13.1.
- [Release notes](https://github.com/nodeca/js-yaml/releases)
- [Changelog](https://github.com/nodeca/js-yaml/blob/master/CHANGELOG.md)
- [Commits](nodeca/js-yaml@3.12.0...3.13.1)

yarn.lock

@@ -4342,9 +4342,9 @@ js-tokens@^3.0.2:
   integrity sha1-mGbfOVECEw449/mWvOtlRDIJwls=
 
 js-yaml@^3.12.0, js-yaml@^3.7.0:
-  version "3.12.0"
-  resolved "https://registry.yarnpkg.com/js-yaml/-/js-yaml-3.12.0.tgz#eaed656ec8344f10f527c6bfa1b6e2244de167d1"
-  integrity sha512-PIt2cnwmPfL4hKNwqeiuz4bKfnzHTBv6HyVgjahA6mPLwPDzjDWrplJBMjHUFxku/N3FlmrbyPclad+I+4mJ3A==
+  version "3.13.1"
+  resolved "https://registry.yarnpkg.com/js-yaml/-/js-yaml-3.13.1.tgz#aff151b30bfdfa8e49e05da22e7415e9dfa37847"
+  integrity sha512-YfbcO7jXDdyj0DGxYVSlSeQNHbD7XPWvrVWeVUujrQEoZzWJIRrCPoyk6kL6IAjAG2IolMK4T0hNUe0HOUs5Jw==
   dependencies:
     argparse "^1.0.7"
     esprima "^4.0.0"