Add `Cargo.lock`

[nick-mobilecoin]

While the guidance from https://doc.rust-lang.org/cargo/faq.html#why-do-binaries-have-cargolock-in-version-control-but-not-libraries says not to commit lock files for libraries, we've found that it is more beneficial to have repeatable development builds. Not having a lock file means that developers may be building with different versions of packages. It can also lead to CI pulling in the newest changes of a package that happens to violate major version changes.

[nick-mobilecoin]

Current dependencies on/for this PR:

• main
  • PR #363
  • PR #364 👈

This comment was auto-generated by Graphite.

[codecov[bot]]

Codecov Report

Merging #364 (cad24ed) into nick/fix-missing-v0.7.1 (01c981e) will not change coverage. The diff coverage is n/a.

@@                   Coverage Diff                    @@
##           nick/fix-missing-v0.7.1     #364   +/-   ##
========================================================
  Coverage                    87.73%   87.73%           
========================================================
  Files                           40       40           
  Lines                         5414     5414           
========================================================
  Hits                          4750     4750           
  Misses                         664      664           

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