feature: replace chars to parse 'cfg(...)' keys

[mdittmer]

Extend instantiate::REPLACE_CHARS to parse 'cfg(...)' keys that are common in Cargo.toml files. Fixes #9.

[mdittmer]

Please let me know how versioning should be managed here. I have included the -alpha suffix for now because, so far, this is not a feature anyone else (including the project maintainers) have asked for. I am happy to update the PR to follow whatever versioning strategy is preferred (including not updating the version in this PR to separate it from release processes).

[facesthe]

The prerelease versioning is alright. However, CI checks are failing due to cargo fm --checkt failing. Could you update the PR?

[mdittmer]

The prerelease versioning is alright. However, CI checks are failing due to cargo fm --checkt failing. Could you update the PR?

Fixed with cargo fmt and updated single-commit PR.

[joshlf]

Thanks for the quick turn-around @facesthe! Any chance you could cut a new release? We'd like to use this fix in Anneal.

[facesthe]

I'll try to get a new release out by the end of the week

[joshlf]

Great, thanks!