Remove dependency on minimal-lexical

[nabilwadih]

This dependency is not actually used anywhere in the project, however it was being pulled in as a dep in the Cargo.toml. This change is simply to remove it from the Cargo.toml

[marshallpierce]

Beyond just trimming unused dependencies being a nice thing for simplicity, another motivation here is to avoid having to do security review on minimal-lexical and its liberal use of unsafe just to be able to use nom in an environment that does reviews on all third party code.

[Geal]

thanks!