build(deps): bump indexmap from 1.5.2 to 1.6.0

Bumps [indexmap](https://github.com/bluss/indexmap) from 1.5.2 to 1.6.0.
- [Release notes](https://github.com/bluss/indexmap/releases)
- [Commits](https://github.com/bluss/indexmap/compare/1.5.2...1.6.0)

Signed-off-by: dependabot[bot] <support@github.com>

Cargo.lock

@@ -1054,12 +1054,9 @@ dependencies = [
 
 [[package]]
 name = "hashbrown"
-version = "0.8.2"
+version = "0.9.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "e91b62f79061a0bc2e046024cb7ba44b08419ed238ecbd9adbd787434b9e8c25"
-dependencies = [
- "autocfg",
-]
+checksum = "00d63df3d41950fb462ed38308eea019113ad1508da725bbedcd0fa5a85ef5f7"
 
 [[package]]
 name = "hdrhistogram"
@@ -1192,9 +1189,9 @@ checksum = "e0bd112d44d9d870a6819eb505d04dd92b5e4d94bb8c304924a0872ae7016fb5"
 
 [[package]]
 name = "indexmap"
-version = "1.5.2"
+version = "1.6.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "4e47a3566dd4fd4eec714ae6ceabdee0caec795be835c223d92c2d40f1e8cf1c"
+checksum = "55e2e4c765aa53a0424761bf9f41aa7a6ac1efa87238f59560640e27fca028f2"
 dependencies = [
  "autocfg",
  "hashbrown",

zebra-network/Cargo.toml

@@ -15,7 +15,7 @@ chrono = "0.4"
 hex = "0.4"
 # indexmap has rayon support for parallel iteration,
 # which we don't use, so disable it to drop the dependencies.
-indexmap = { version = "1.5", default-features = false }
+indexmap = { version = "1.6", default-features = false }
 pin-project = "0.4"
 rand = "0.7"
 serde = { version = "1", features = ["serde_derive"] }