Bump file to 2.3.1 (#8807)

packages/flutter_driver/pubspec.yaml

@@ -8,7 +8,7 @@ environment:
   sdk: '>=1.19.0 <2.0.0'
 
 dependencies:
-  file: 2.3.0
+  file: 2.3.1
   json_rpc_2: '^2.0.0'
   matcher: '>=0.12.0 <1.0.0'
   meta: ^1.0.4

packages/flutter_tools/pubspec.yaml

@@ -12,7 +12,7 @@ dependencies:
   args: ^0.13.4
   coverage: ^0.8.0
   crypto: '>=1.1.1 <3.0.0'
-  file: 2.3.0
+  file: 2.3.1
   http: ^0.11.3+12
   intl: '>=0.14.0 <0.15.0'
   json_rpc_2: ^2.0.0