build: Remove unnecessary std::ref, causing compilation issues with Boost 1.70.0

Refs: #4923
Change-Id: Idba1abe89161b11b1ec80fdceac51e2b00ed507b
diff --git a/.gitmodules b/.gitmodules
index 0b8f2ee..edc03cc 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -1,3 +1,3 @@
 [submodule "websocketpp"]
     path = websocketpp
-    url = https://github.com/zaphoyd/websocketpp.git
+    url = https://github.com/cawka/websocketpp.git