Bump bn.js from 4.11.8 to 5.1.1 (#45)

Bumps [bn.js](https://github.com/indutny/bn.js) from 4.11.8 to 5.1.1.
- [Release notes](https://github.com/indutny/bn.js/releases)
- [Changelog](https://github.com/indutny/bn.js/blob/master/CHANGELOG.md)
- [Commits](https://github.com/indutny/bn.js/compare/v4.11.8...v5.1.1)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

packages/ripple-binary-codec/package.json

@@ -13,7 +13,7 @@
   },
   "dependencies": {
     "babel-runtime": "^6.6.1",
-    "bn.js": "^4.11.3",
+    "bn.js": "^5.1.1",
     "create-hash": "^1.1.2",
     "decimal.js": "^10.2.0",
     "inherits": "^2.0.1",

packages/ripple-binary-codec/yarn.lock

@@ -785,10 +785,10 @@ binary-extensions@^1.0.0:
   resolved "https://registry.yarnpkg.com/binary-extensions/-/binary-extensions-1.13.1.tgz#598afe54755b2868a5330d2aff9d4ebb53209b65"
   integrity sha512-Un7MIEDdUC5gNpcGDV97op1Ywk748MpHcFTHoYs6qnj1Z3j7I53VG3nwZhKzoBZmbdRNnb6WRdFlwl7tSDuZGw==
 
-bn.js@^4.11.3:
-  version "4.11.8"
-  resolved "https://registry.yarnpkg.com/bn.js/-/bn.js-4.11.8.tgz#2cde09eb5ee341f484746bb0309b3253b1b1442f"
-  integrity sha512-ItfYfPLkWHUjckQCk8xC+LwxgK8NYcXywGigJgSwOP8Y2iyWT4f2vsZnoOXTTbo+o5yXmIUJ4gn5538SO5S3gA==
+bn.js@^5.1.1:
+  version "5.1.1"
+  resolved "https://registry.yarnpkg.com/bn.js/-/bn.js-5.1.1.tgz#48efc4031a9c4041b9c99c6941d903463ab62eb5"
+  integrity sha512-IUTD/REb78Z2eodka1QZyyEk66pciRcP6Sroka0aI3tG/iwIdYLrBD62RsubR7vqdt3WyX8p4jxeatzmRSphtA==
 
 brace-expansion@^1.1.7:
   version "1.1.11"