Updated C++ SDK Version and Version.bzl

PiperOrigin-RevId: 263181187

Author: amablue

cpp_sdk_version.json

@@ -1,5 +1,5 @@
 {
-  "released": "6.2.2",
-  "stable": "6.2.2",
-  "head": "6.2.2"
+  "released": "6.3.0",
+  "stable": "6.3.0",
+  "head": "6.3.0"
 }