Downgrade dev-dep tokio to support MSRV 1.65

[jayvdb]

Description

• Downgrade dev-dep tokio so that builds on Rust 1.65 still work
• Set MSRV in Cargo.toml
• Add Cargo.lock so that it is possible to determine what versions of deps are able to build on the MSRV

Checklist

• [ ] Formatted code using cargo fmt --all
• [ ] Linted code using clippy
  • [ ] with reqwest feature: cargo clippy --manifest-path influxdb/Cargo.toml --all-targets --no-default-features --features serde,derive,reqwest-client-rustls -- -D warnings
  • [ ] with surf feature: cargo clippy --manifest-path influxdb/Cargo.toml --all-targets --no-default-features --features serde,derive,hyper-client -- -D warnings
• [ ] Updated README.md using cargo doc2readme -p influxdb --expand-macros
• [ ] Reviewed the diff. Did you leave any print statements or unnecessary comments?
• [ ] Any unfinished work that warrants a separate issue captured in an issue with a TODO code comment