Merge pull request #1619 from hypothesis/dependabot/npm_and_yarn/babel-plugin-istanbul-6.0.0

Bump babel-plugin-istanbul from 5.2.0 to 6.0.0

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",