[README] Update Xcode version to Xcode 8.3 Beta 3
diff --git a/README.md b/README.md
index fe7b822..6d91388 100644
--- a/README.md
+++ b/README.md
@@ -53,7 +53,7 @@
macOS, Ubuntu Linux LTS, and the latest Ubuntu Linux release are the current
supported host development operating systems.
-For macOS, you need [Xcode 8.3 Beta 2](https://developer.apple.com/xcode/downloads/).
+For macOS, you need [Xcode 8.3 Beta 3](https://developer.apple.com/xcode/downloads/).
For Ubuntu, you'll need the following development dependencies:
