Update Rust crate indexmap to v1.8.1

Author: renovate-bot

Cargo.lock

@@ -60,7 +60,7 @@ futures-util = "=0.3.21"
 hex = "=0.4.3"
 http = "=0.2.6"
 hyper = { version = "=0.14.17", features = ["client", "http1"] }
-indexmap = { version = "=1.8.0", features = ["serde-1"] }
+indexmap = { version = "=1.8.1", features = ["serde-1"] }
 tikv-jemallocator = { version = "=0.4.3", features = ['unprefixed_malloc_on_supported_platforms', 'profiling'] }
 lettre = { version = "=0.10.0-rc.4", default-features = false, features = ["file-transport", "smtp-transport", "native-tls", "hostname", "builder"] }
 minijinja = "=0.15.0"