AK: Mark HashTable::size_in_bytes() as constexpr

Author: https://github.com/Hendiadyoin1
Commit: https://github.com/SerenityOS/serenity/commit/93cf01ad7db
Pull-request: https://github.com/SerenityOS/serenity/pull/9405
Reviewed-by: https://github.com/Dexesttp
Reviewed-by: https://github.com/sin-ack ✅

AK/HashTable.h

@@ -378,7 +378,7 @@ private:
         }
     }
 
-    [[nodiscard]] static size_t size_in_bytes(size_t capacity)
+    [[nodiscard]] static constexpr size_t size_in_bytes(size_t capacity)
     {
         if constexpr (IsOrdered) {
             return sizeof(BucketType) * capacity;