xcode update for mac builds

Summary: Avoid using old xcode which CircleCI say is deprecated.

Reviewed By: patricklabatut

Differential Revision: D29538176

fbshipit-source-id: 1e2ae4845d42365c778536446958966bbecf188c

Author: bottler

.circleci/config.in.yml

@@ -209,7 +209,7 @@ jobs:
   binary_macos_wheel:
     <<: *binary_common
     macos:
-      xcode: "9.4.1"
+      xcode: "12.0"
     steps:
       - checkout
       - run:

.circleci/config.yml

@@ -209,7 +209,7 @@ jobs:
   binary_macos_wheel:
     <<: *binary_common
     macos:
-      xcode: "9.4.1"
+      xcode: "12.0"
     steps:
       - checkout
       - run: