update xcode CI config to 9.4.1

Summary: This addresses #375. Change circleci mac version to 9.4.1 just like torchvision did in https://github.com/pytorch/vision/issues/2629 .

Reviewed By: gkioxari

Differential Revision: D23866112

fbshipit-source-id: c5019618bcb7da8f950123fee201beaad55fecab

.circleci/config.in.yml

@@ -185,7 +185,7 @@ jobs:
   binary_macos_wheel:
     <<: *binary_common
     macos:
-      xcode: "9.0"
+      xcode: "9.4.1"
     steps:
       - checkout
       - run:

.circleci/config.yml

@@ -185,7 +185,7 @@ jobs:
   binary_macos_wheel:
     <<: *binary_common
     macos:
-      xcode: "9.0"
+      xcode: "9.4.1"
     steps:
       - checkout
       - run: