hashbrown 0.15.1 requires Rust 1.65 which breaks 1.63 MSRV here

[eaufavor]

rust-lang/hashbrown#585

[cuviper]

I'm not going to restrict the maximum semver-compatible dependency version, and this is otherwise inactionable on indexmap's part. When you need to build on 1.63, you can run cargo update -p hashbrown --precise 0.15.0. If you have multiple hashbrown in your dependency tree, you'll need to disambiguate [email protected] that you're "updating".