Upgrade dependencies

Not upgraded:

• proc-macro-crate – the latest version actually allows getting rid of extern crate self as crate_name; by detecting when the proc-macro is used from the "parent" crate, but it seems like proc-macro-crate isn't used properly in the first place (lots of zbus instead of #zbus in quote! blocks). I might write another PR for this when I get more time.
• enumflags2 – RawBitFlags was renamed to BitFlag but it seems the underlying integer ::Type is also no longer accessible, so not sure how to upgrade. (changelog)