chore: add Hayden (@hds) to codeowners (#3410)

I'd like to get notifications on these explicitly and I'm doing a lot of
the reviews and maintenance these days, so I think it makes sense.

Also removed Zeki (@zekisherif) as GitHub is telling me that the account
doesn't exist any more.

Author: hds

.github/CODEOWNERS

@@ -1,12 +1,9 @@
-# Eliza should review everything unassigned.
-*                               @hawkw @tokio-rs/tracing
+# Eliza or Hayden should review everything unassigned.
+*                               @hawkw @hds @tokio-rs/tracing
 
 # tracing-error and tracing-flame were contributed by Jane.
 /tracing-error/                 @yaahc @tokio-rs/tracing
 /tracing-flame/                 @yaahc @tokio-rs/tracing
 
 # David contributed the Registry implementation.
 /tracing-subscriber/registry    @davidbarsky @hawkw @tokio-rs/tracing
-
-# Zeki contributed the TracingAppender implementation
-/tracing-appender/              @zekisherif  @tokio-rs/tracing