Rollup merge of #148013 - Mark-Simulacrum:relnotes, r=Mark-Simulacrum

1.91.0 release notes

This imports rust-lang/rust#147010 into a PR in preparation for the release next week. It also imports a subset of the Cargo release notes (cc ```@rust-lang/cargo).```

r? ```@rust-lang/release```

```@triagebot``` ping relnotes-interest-group

Author: Zalathar