Section [metadata] seems to no longer be produced by nightly cargo

[dbartussek]

Describe the bug
It seems the nightly compiler no longer puts the hash into a metadata section, but instead in the package list at the "checksum" key. This breaks cargo deny check ban.

To Reproduce
Steps to reproduce the behavior:

1. Initialize a new project
2. Add any dependency
3. Compile with nightly
4. Initialize and run cargo deny check ban
5. An error message "unable to find metadata section in Cargo.lock".

Expected behavior
The ban checker should probably fall back on the "checksum" field if the "metadata" section cannot be found.

[Jake-Shadle]

Ahh interesting, I was aware this change was coming, luckily I am doing a separate change that I can fold a fix for this into, thanks for the report!