Give libs, libs-api, and libs-contributors write access to wg-allocators

The allocator API overlaps with libs quite a bit, so allow these teams
access for issue triage.

Author: tgross35

repos/rust-lang/wg-allocators.toml

@@ -5,4 +5,7 @@ homepage = "http://bit.ly/hello-wg-allocators"
 bots = []
 
 [access.teams]
+libs = "write"
+libs-api = "write"
+libs-contributors = "write"
 wg-allocators = "maintain"