Update flow-bin to the latest version � (#727)

Summary:
## The devDependency [flow-bin](https://github.com/flowtype/flow-bin) was updated from `0.114.0` to `0.115.0`.
This version is **not covered** by your **current version range**.

If you don’t accept this pull request, your project will work just like it did before. However, you might be missing out on a bunch of new features, fixes and/or performance improvements from the dependency update.

 ---

**Publisher:** [mroch](https://www.npmjs.com/~mroch)
**License:** MIT

[Find out more about this release](https://github.com/flowtype/flow-bin).

 ---

<details>
  <summary>FAQ and help</summary>

  There is a collection of [frequently asked questions](https://greenkeeper.io/faq.html). If those don’t help, you can always [ask the humans behind Greenkeeper](https://github.com/greenkeeperio/greenkeeper/issues/new).
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Your [Greenkeeper](https://greenkeeper.io) bot 🌴
Pull Request resolved: https://github.com/facebook/flipper/pull/727

Reviewed By: mweststrate

Differential Revision: D19288142

Pulled By: passy

fbshipit-source-id: 1285148e9e32660462e196923afbfaf2764bc04c

.flowconfig

@@ -35,4 +35,4 @@ untyped-import
 untyped-type-import
 
 [version]
-0.114.0
+0.115.0

package.json

@@ -100,7 +100,7 @@
     "eslint-plugin-prettier": "^3.1.1",
     "eslint-plugin-react": "^7.16.0",
     "eslint-plugin-relay": "^1.4.1",
-    "flow-bin": "0.114.0",
+    "flow-bin": "0.115.0",
     "glob": "^7.1.2",
     "jest": "^24.7.1",
     "jest-fetch-mock": "^3.0.0",

yarn.lock

@@ -4190,10 +4190,10 @@ flipper-doctor@^0.4.1:
     "@types/node" "^12.12.12"
     envinfo "^7.4.0"
 
-flow-bin@0.114.0:
-  version "0.114.0"
-  resolved "https://registry.yarnpkg.com/flow-bin/-/flow-bin-0.114.0.tgz#9079c5fcdf08fab4db91616f38994e9b7d035842"
-  integrity sha512-hewufX0nbnhemQn5XtJ97nEFNqoBclPBAZ54aY3jKuZJnLpwqB7Doaplet3M26TOh2NchBsU0+lUkM8oVna2VA==
+flow-bin@0.115.0:
+  version "0.115.0"
+  resolved "https://registry.yarnpkg.com/flow-bin/-/flow-bin-0.115.0.tgz#22e3ad9e5c7198967de80138ba8a9154ff387960"
+  integrity sha512-xW+U2SrBaAr0EeLvKmXAmsdnrH6x0Io17P6yRJTNgrrV42G8KXhBAD00s6oGbTTqRyHD0nP47kyuU34zljZpaQ==
 
 flow-parser@0.*:
   version "0.110.0"