chore(turbopack): Update indexmap dependency from 1.x to 2.x (#72429)
I noticed we were using a pretty old version of indexmap, this updates that.
`indexmap 1.9.3` still exists in the lockfile as there are some other dependencies we have (mostly `wasmer`) that pull it, but as those dependencies are updated, we'll get rid of it.
I specified the lower version range bound as `2.5.0` instead of `2.6.0` because I wanted to avoid introducing [yet another minor version of hashbrown](https://github.com/indexmap-rs/indexmap/blob/master/RELEASES.md), which might *slightly* help with compilation times. This is just a lower bound, so eventually we'll end up on `2.6.0` (or a later version) if dependency asks for it.
Closes PACK-3406