Dependency upgrade requests for 0.46

[benesch]

Hey @iliana, I thought it might be helpful to enumerate all the dependency upgrades that would ideally be included in v0.46:

• Update pin-project to v1.0 (merge Update pin-project dependency to 1.0 #1847)
• Use dirs-next v2.0 instead of dirs (merge Update from dirs to dirs-next #1846)
• Update base64 to v0.13 (merge Bump base64 crate to 0.13 #1833; close Update base64 dependency to 0.13 #1837)
• Update to hmac v0.10 (rusoto_signature: upgrade to hmac 0.10 #1827)
• Disable chrono default features (Disable chrono default features #1829)
• Upgrade to Tokio v0.3 (no PR yet, but WIP here: MaterializeInc@f78b21a)

Somehow the Rust ecosystem moves fast enough that these all piled up in the few months since the last release.

[joshtriplett]

Please also consider upgrading hyper-rustls to 0.21 (which in turn avoids a dependency on older base64).

[benesch]

I've gathered all of these changes up into a fork that I'm in the process of releasing. See: #1651 (comment).