Handle "Binary files differ" lines

[uniphil]

Adds a small tweak to #26 to restore an unrelated testcase

thanks @sourcefrog!

[uniphil]

clippy is complaining about not eliding lifetimes. for the moment i'm going to ignore that, seems like potentially a MSRV thing (i forget if i made an msrv policy).

i put the tab back that was lost. i like the test case being as literal as possible, but this also seems likely to happen again (even from an editor automatically converting to space or stripping) so maybe an escaped \t is a better choice here.

[sourcefrog]

Thanks!

[whitty]

If it is useful to you I have resolved the clippy issues here gitpatch-rs/gitpatch#7 (in the fork) - as part of my attempt to merge together as many outstanding PRs as practical.

You can see the pieces I've pulled together in the comment on that PR, including grabbing this PR, since github doesn't really allow stacking PRs on foreign repos its a little hard to navigate for now.