Update bootstrap 4.6.1

WebCms/Content/bootstrap/_navbar.scss

@@ -136,8 +136,12 @@
   height: 1.5em;
   vertical-align: middle;
   content: "";
-  background: no-repeat center center;
-  background-size: 100% 100%;
+  background: 50% / 100% 100% no-repeat;
+}
+
+.navbar-nav-scroll {
+  max-height: $navbar-nav-scroll-max-height;
+  overflow-y: auto;
 }
 
 // Generate series of `.navbar-expand-*` responsive classes for configuring
@@ -199,6 +203,10 @@
           }
         }
 
+        .navbar-nav-scroll {
+          overflow: visible;
+        }
+
         .navbar-collapse {
           display: flex !important; // stylelint-disable-line declaration-no-important