[With example] Make copy constructible

Source:
```cpp
std::unordered_map, std::string> tmp;
```

Result:
```sh
/home/matheus/programmieren/c++/argo/src/database/User.cpp:508:87: required from here
508 | std::unordered_map, std::string> tmp;
| ^~~
/usr/include/c++/15.2.1/bits/hashtable.h:210:51: Fehler: statische Assertion fehlgeschlagen: hash function must be copy constructible
210 | static_assert(is_copy_constructible<_Hash>::value,
| ^~~~~
```