Upgrade to indexmap v2

No code changes are required for the current uses of indexmap.

I also updated `toml_edit` to get its update to `indexmap 2`, and
`gix-hashtable` to align them all on `hashbrown 0.14`.

Author: cuviper

Cargo.lock

@@ -48,7 +48,7 @@ http-auth = { version = "0.1.6", default-features = false }
 humantime = "2.0.0"
 ignore = "0.4.7"
 im-rc = "15.0.0"
-indexmap = "1"
+indexmap = "2"
 itertools = "0.10.0"
 jobserver = "0.1.26"
 lazy_static = "1.3.0"