Release v0.12.0

Release v0.12.0

• Bump rustls, make ct_logs dependency optional
• Add container attach method (thanks @antoinert )
• Add resize container tty method (thanks @antoinert )
• Fix bugs in JSON parser:
  • handle buffers ending in closing brace and not being parseable
  • handle newlines inside of JSON payload
• Let users specify a timeout
• Fix clippy failures on Rust version 1.59 (thanks @edmorley )
• Make all SSL dependencies optional (thanks @edmorley )
• Switch from pin-project to pin-project-lite dependency (thanks @edmorley )
• Clean up tokio features (thanks @edmorley )
• Enforce cargo fmt in CI
• Make all Docker errors generic
• Bump bollard-stubs models to a pre-1.42 API release
• Add PartialEq to all options