Bump Xcode version used by CircleCI (#55)

AliSoftware · web-flow · commit a738240828f1 · 2018-03-15T15:52:29.000+01:00
diff --git a/circle.yml b/circle.yml
@@ -1,6 +1,6 @@
 machine:
   xcode:
-    version: 8.2
+    version: 9.2
 
 dependencies:
   pre:
