Update dev dependencies

[jayvdb]

Description

Update dev-dependencies indoc and async-std

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

[msrd0]

Is there a particular reason for updating async-std to a semver-compatible version? Do we need any features/bugfixes introduced since the version we specified?

[jayvdb]

The main feature is async-std now has I/O safe traits sunfishcode/io-lifetimes#38 , but there are also many other bug fixes since async-std v1.6.5 which was released 4 years ago, including several panics.