Update flow.

.flowconfig

@@ -10,3 +10,4 @@ suppress_comment=\\(.\\|\n\\)*\\$FlowFixedInNextDeploy
 suppress_comment=\\(.\\|\n\\)*\\$FlowExpectedError
 
 unsafe.enable_getters_and_setters=true
+munge_underscores=true

package.json

@@ -18,7 +18,7 @@
     "eslint-plugin-babel": "^4.0.0",
     "eslint-plugin-flowtype": "^2.28.2",
     "eslint-plugin-react": "^6.10.0",
-    "flow-bin": "^0.40.0",
+    "flow-bin": "^0.43.1",
     "glob": "^7.1.1",
     "istanbul-api": "^1.1.0",
     "istanbul-lib-coverage": "^1.0.0",

yarn.lock

@@ -1397,9 +1397,9 @@ flat-cache@^1.2.1:
     graceful-fs "^4.1.2"
     write "^0.2.1"
 
-flow-bin@^0.40.0:
-  version "0.40.0"
-  resolved "https://registry.yarnpkg.com/flow-bin/-/flow-bin-0.40.0.tgz#e10d60846d923124e47f548f16ba60fd8baff5a5"
+flow-bin@^0.43.1:
+  version "0.43.1"
+  resolved "https://registry.yarnpkg.com/flow-bin/-/flow-bin-0.43.1.tgz#0733958b448fb8ad4b1576add7e87c31794c81bc"
 
 for-in@^1.0.1:
   version "1.0.1"