AK: Make HashTable with capacity constructor explicit

Author: https://github.com/bgianfo
Commit: https://github.com/SerenityOS/serenity/commit/15b94ec1fdd
Pull-request: https://github.com/SerenityOS/serenity/pull/6234

AK/HashTable.h

@@ -87,7 +87,7 @@ class HashTable {
 
 public:
     HashTable() = default;
-    HashTable(size_t capacity) { rehash(capacity); }
+    explicit HashTable(size_t capacity) { rehash(capacity); }
 
     ~HashTable()
     {