Floating dependency versions

[commonquail]

The following dependencies in master as of 0f642a6 use only wildcards:

• getopts
• time
• dirs
• nix
• ctrlc

Another 5 are pinned to exact versions.

the floating versions on master make this kind of harder that it should be

Effectively impossible. I was going to submit another change to pin the remaining dependency versions for precisely that reason but hadn't gotten to it yet. Why do you want to avoid that?

Originally posted by @commonquail in #19 (comment)

Apparently all versions are pinned in the two release-* branches.

Over time, this is liable to invite breakage of master by incompatibilities introduced in new versions of the unpinned dependencies; and relative to to the README this has already happened with getopts v0.2.20 and libloading v0.6.0.

It's unclear if this is an oversight or deliberate, and if so, what the motivation behind is.

[foucault]

You're probably correct. In the longer term it's better to keep dependencies manageable. There's lots of breakage going around with rust libraries so in addition to keeping #19 happy this also has the benefit of keeping master buildable. Dependencies can be updated later when/if needed. Of course we'll have to update minimum rust versions.