Inconsistent behavior on run()
Hi @dom96,

When specifying settings (port, bind address, ...), the domain is set to `AF_UNSPEC`. However, without settings, the domain is set to `AF_INET` 

This make
https://github.com/dom96/httpbeast/blob/b33dba93a134faa2adc3b991cb69890375987076/src/httpbeast.nim#L464
and 
https://github.com/dom96/httpbeast/blob/b33dba93a134faa2adc3b991cb69890375987076/src/httpbeast.nim#L492
have different behavior (except if we specify `domain` for the first one)

Regards,

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Related to https://github.com/the-benchmarker/web-frameworks/pull/4554