fix: add verification_phone_number property to create sign request (box/box-openapi#515)

Author: box-sdk-build

.codegen.json

@@ -1 +1 @@
-{ "engineHash": "41feeaa", "specHash": "3dc6f70", "version": "0.6.0" }
+{ "engineHash": "41feeaa", "specHash": "1080bb4", "version": "0.6.0" }