Bump indexmap from 1.8.2 to 1.9.1 (#381)

Bumps [indexmap](https://github.com/bluss/indexmap) from 1.8.2 to 1.9.1.
- [Release notes](https://github.com/bluss/indexmap/releases)
- [Changelog](https://github.com/bluss/indexmap/blob/master/RELEASES.md)
- [Commits](indexmap-rs/indexmap@1.8.2...1.9.1)

---
updated-dependencies:
- dependency-name: indexmap
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <[email protected]>

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

Cargo.lock

@@ -18,7 +18,7 @@ bytes = "1"
 futures = "0.3.21"
 hostname = "0.3.0"
 http = "0.2.8"
-indexmap = "1.8.2"
+indexmap = "1.9.1"
 openapiv3 = "=1.0.1"
 paste = "1.0.7"
 percent-encoding = "2.1.0"