Update the bazelci to use xcode 11.3 for tests.

PiperOrigin-RevId: 311578731

.bazelci/presubmit.yml

diff --git a/.bazelci/presubmit.yml b/.bazelci/presubmit.yml
index 77199ce..cdde891 100644
--- a/.bazelci/presubmit.yml
+++ b/.bazelci/presubmit.yml
@@ -1,7 +1,7 @@
 ---
 platforms:
   macos:
-    xcode_version: "11.1"
+    xcode_version: "11.3"
     bazel: last_downstream_green
     build_targets:
     - "//:tulsi"