Prevent illegal request path from crashing program

[cyqsimon]

I experienced a service crash today due to a request that contains an illegal character in its path. The request seems to be a malicious vulnerability scan, but it shouldn't crash the program nonetheless. This PR makes sure this doesn't happen.

Logs:

Dec 06 04:07:59 HOSTNAME miniserve[1012]: thread 'actix-rt|system:0|arbiter:1' panicked at 'called `Result::unwrap()` on an `Err` value: http::Error(InvalidUri(InvalidUriChar))', /build/path/miniserve-0.24.0/src/listing.rs:171:10

[svenstaro]

Thanks! Could you perhaps also add a test for this? For extra points, proptest would be perfect for finding stuff such as this!

[cyqsimon]

Ugh. That's not going to be trivial because I don't actually know what the offending request was. And going the distance to learn and add a new testing framework needs more time than I'm willing to commit. Sorry ¯\_(ツ)_/¯.

And to be honest I find it a bit overkill to test for what amounts to an "avoid using unwrap" anyways.

[svenstaro]

Ok don't worry. I'll add the test case.