change gz check to check suffix of path

[jchorl]

I just had this fail because I put a .fna file in a tempdir. Calling mktemp rolled me a path with gz right in the middle (/foo/xxgzxx/myfile.fna).

I'm wondering if we can make this more strict. I can't think of a good case where a gz would have gz not as it's suffix. Maybe some folks use .gzip but I can't recall seeing that.

Thanks!

[kbessonov1984]

Sure, I did not realize that case scenario where gz could indeed be present in the path. I like your modification and will merge it after the CI unit tests

[kbessonov1984]

This PR will also be incorporated in the build #2 in conda with the same release version 2.0.0. Many thanks

[jchorl]

Thank you!!