Bump babel-plugin-istanbul from 5.2.0 to 6.0.0

Bumps [babel-plugin-istanbul](https://github.com/istanbuljs/babel-plugin-istanbul) from 5.2.0 to 6.0.0.
- [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/v5.2.0...v6.0.0)
Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

package.json

@@ -20,7 +20,7 @@
     "autoprefixer": "^9.4.7",
     "aws-sdk": "^2.345.0",
     "babel-plugin-angularjs-annotate": "^0.10.0",
-    "babel-plugin-istanbul": "^5.1.0",
+    "babel-plugin-istanbul": "^6.0.0",
     "babel-plugin-mockable-imports": "^1.5.1",
     "babel-plugin-transform-async-to-promises": "^0.8.6",
     "babelify": "^10.0.0",