Upgrade to Rust 1.85

[alamb]

Is your feature request related to a problem or challenge?

Rust 1.85 is released: https://blog.rust-lang.org/2025/02/20/Rust-1.85.0.html

Currently DataFusion uses the version of rust specified here:
https://github.com/apache/datafusion/blob/main/rust-toolchain.toml

Describe the solution you'd like

I would like to:

1. Update the tool chain to 1.85 (likely requires fixing / updating clippy)
2. Update the MSRV (min supported rust version) to the next version:

   datafusion/Cargo.toml

   Line 69 in 188e0d3

   rust-version = "1.81.0"

Describe alternatives you've considered

No response

Additional context

I think this would be a good first issue as it is relatively mechanical