events: fix violation of symbol naming convention

Capital letter is followed after 'k' prefix.

PR-URL: #45978
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Minwoo Jung <nodecorelab@gmail.com>

lib/internal/event_target.js

@@ -56,7 +56,7 @@ const kEvents = Symbol('kEvents');
 const kIsBeingDispatched = Symbol('kIsBeingDispatched');
 const kStop = Symbol('kStop');
 const kTarget = Symbol('kTarget');
-const kHandlers = Symbol('khandlers');
+const kHandlers = Symbol('kHandlers');
 const kWeakHandler = Symbol('kWeak');
 
 const kHybridDispatch = SymbolFor('nodejs.internal.kHybridDispatch');