chore(Cargo.toml): bump version to 0.8.0

[vdice]

• Bumps the version to the next minor release

This is more a 'suggestion to release'. I'm not as up-to-speed on if we wanted to wait for certain features/changes before releasing 0.8.0 or not. My motivation stems from https://github.com/deislabs/wagi needing the changes in #287 to succesfully rev its bindle version to the latest and greatest.

As it stands, this is the changelog since 0.7.1:

• chore(Cargo.toml): bump version to 0.8.0 c94e4aa (Vaughn Dice)
• Fix for crate consumers not finding Signature trait methods (Fix for crate consumers not finding Signature trait methods #287) d46c371 (itowlson)
• fix(ci): Uses the correct var name 053cb8a (Taylor Thomas)
• feat(ci): Adds support for m1 Macs and auto crate pushing f0dd36e (Taylor Thomas)
• feat(cli): Adds support for standalone tarballs to client 5a05dd2 (Taylor Thomas)
• feat(standalone): Adds tarball support to standalone bindles 3f3fbfc (Taylor Thomas)
• fix(*): Fixes various clippy lints 2bc895b (Taylor Thomas)
• chore(Cargo.toml): bump tracing-subscriber dependency per CI failure: thread_local nested dep #279 (chore(Cargo.toml): bump tracing-subscriber dependency per #279 #281) 3de704c (Vaughn Dice)
• docs(reference-spec.md): fix SemVer 2 link (docs(reference-spec.md): fix SemVer 2 link #278) d2fcdbd (Vaughn Dice)

[thomastaylor312]

@vdice I think I'm fine with cutting a release. My issue is that we have been promising to add verification support to the client for 2 releases now. If we are all ok pushing that off, then I am fine with a new release!

[radu-matei]

Given that this unblocks Wagi, I'm also ok with cutting a release now, and focusing on client the verification for 0.9.

LGTM

[vdice]

Thanks @thomastaylor312 @radu-matei. Will merge and proceed with creating the release.