Fix warning for windows

Correct my previous commit

chore: silence Visual Studio 2022 (17.3.0) warning

without the following warning is emitted:

```
include\function2\function2.hpp(1176): warning C4305: '<function-style-cast>': truncation from 'bool (__cdecl *)(void)' to 'bool'
```

Fix issue #50

Release 4.2.0

* Includes minor maintainance and stability patches from the last year
* Closes #46

Fix reference types in the return type

* Closes #35

Happy new year!

Attempt to fix the Appveyor build

Use the travis script of Naios/continuable

Implement wrapping of class members

* Closes #10