Bump decimal.js from 5.0.8 to 10.2.0 (#38)

Bumps [decimal.js](https://github.com/MikeMcl/decimal.js) from 5.0.8 to 10.2.0.
- [Release notes](https://github.com/MikeMcl/decimal.js/releases)
- [Changelog](https://github.com/MikeMcl/decimal.js/blob/master/CHANGELOG.md)
- [Commits](https://github.com/MikeMcl/decimal.js/compare/v5.0.8...v10.2.0)

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

packages/ripple-binary-codec/package.json

@@ -15,7 +15,7 @@
     "babel-runtime": "^6.6.1",
     "bn.js": "^4.11.3",
     "create-hash": "^1.1.2",
-    "decimal.js": "^5.0.8",
+    "decimal.js": "^10.2.0",
     "inherits": "^2.0.1",
     "lodash": "^4.17.15",
     "ripple-address-codec": "^3.0.4"