Update dependencies of async-log-attributes and make it to be optional

[koushiro]

Signed-off-by: koushiro [email protected]

• Update proc-maroc2, syn and quote to v1.0
• Make async-log-attributes to be optional (close Expose a feature to disable proc-macro support #6)

[koushiro]

@yoshuawuyts PTAL :)
Could you publish a patch version if the PR is merged ?

[Keruspe]

Now that tide depends on femme, it pulls in async-log-attributes and it's sad to see proc-macro2/syn/quote 0.x get back in the dependency tree.
This would be greatly appreciated to avoid duplicate dependencies.

@yoshuawuyts BTW, when you merge and make a release out of this, you should s/runtime/async-log/ in several places