Bump babel-plugin-istanbul from 5.1.2 to 5.1.3

Bumps [babel-plugin-istanbul](https://github.com/istanbuljs/babel-plugin-istanbul) from 5.1.2 to 5.1.3.
- [Release notes](https://github.com/istanbuljs/babel-plugin-istanbul/releases)
- [Changelog](https://github.com/istanbuljs/babel-plugin-istanbul/blob/master/CHANGELOG.md)
- [Commits](https://github.com/istanbuljs/babel-plugin-istanbul/compare/v5.1.2...v5.1.3)
Signed-off-by: dependabot[bot] <support@dependabot.com>

yarn.lock

@@ -1541,9 +1541,9 @@ babel-plugin-check-es2015-constants@^6.22.0:
     babel-runtime "^6.22.0"
 
 babel-plugin-istanbul@^5.1.0:
-  version "5.1.2"
-  resolved "https://registry.yarnpkg.com/babel-plugin-istanbul/-/babel-plugin-istanbul-5.1.2.tgz#d8c2e2e83f72695d6bfdcd297719c66161d5f0f9"
-  integrity sha512-U3ZVajC+Z69Gim7ZzmD4Wcsq76i/1hqDamBfowc1tWzWjybRy70iWfngP2ME+1CrgcgZ/+muIbPY/Yi0dxdIkQ==
+  version "5.1.3"
+  resolved "https://registry.yarnpkg.com/babel-plugin-istanbul/-/babel-plugin-istanbul-5.1.3.tgz#202d20ffc96a821c68a3964412de75b9bdeb48c7"
+  integrity sha512-IFyehbvRRwdBlI1lDp+FaMsWNnEndEk7065IB8NhzBX+ZKLPwPodgk4I5Gobw/8SNUUzso2Dv3hbqRh88eiSCQ==
   dependencies:
     find-up "^3.0.0"
     istanbul-lib-instrument "^3.2.0"