fix: remove unneeded spin-core dep from key-value-azure factor

[kate-goldenring]

No description provided.

[kate-goldenring]

It looks like we are using async-trait from core in several of the factors. @rylev is there a motivation around re-exporting from core and importing from there rather than taking a direct dependency on async-trait?

[rylev]

Nope. I think this a good change.

[kate-goldenring]

@itowlson runners are still failing right? Or should i do something to re-kick the tests here?

[itowlson]

@kate-goldenring as far as I know runners are still failing

@rylev would you be in favour of making this change in other crates? I can pick that up if so, no need to hold up this PR

[rylev]

The motivation behind re-exporting async-trait was (I believe) to ensure that consumers of spin-core all could align on the version used by spin-core. Within the spin codebase this isn't a huge issue since everyone should be just using the workspace dependency which ensures everyone is using the same version. This is more helpful with embedders of Spin who cannot rely on the workspace dependency to make sure their versions align.

Given that async-trait is definitely a part of spin-core's public interface, I think it makes sense to use the version of async-trait exposed by spin-core _when the consuming crate is already using spin-core.