subscriber: add "unicode-case" and "unicode-perl" features to regex dependency (tokio-rs#2566)

 ## Motivation

Missing features for the `regex` crate were causing build time errors
due to the the use of unicode characters in the regex without using
the proper features within the regex crate

 ## Solution

Add the missing feature flags.

Fixes tokio-rs#2565

Authored-by: Devin Bidwell <[email protected]>

Author: dbidwell94

tracing-subscriber/Cargo.toml

@@ -42,7 +42,7 @@ tracing-core = { path = "../tracing-core", version = "0.2", default-features = f
 # only required by the `env-filter` feature
 tracing = { optional = true, path = "../tracing", version = "0.2", default-features = false }
 matchers = { optional = true, version = "0.1.0" }
-regex = { optional = true, version = "1.6.0", default-features = false, features = ["std"] }
+regex = { optional = true, version = "1.6.0", default-features = false, features = ["std", "unicode-case", "unicode-perl"] }
 smallvec = { optional = true, version = "1.9.0" }
 once_cell = { optional = true, version = "1.13.0" }