Use no-switch-default on clang

clang-18 improves this check so that we can actually use it.  Enable it
and fix all violations.

Change-Id: Ibe4ce19c423d447a4cbe593d1abba948362426af
Signed-off-by: Ed Tanous <ed@tanous.net>
diff --git a/src/json_html_serializer.cpp b/src/json_html_serializer.cpp
index 5473b1d..3e0e5f8 100644
--- a/src/json_html_serializer.cpp
+++ b/src/json_html_serializer.cpp
@@ -539,7 +539,7 @@
             out += "null";
             return;
         }
-        case nlohmann::json::value_t::binary:
+        default:
         {
             // Do nothing;  Should never happen.
             return;