change code owner (#51)

*Issue #, if available:*

*Description of changes:*

Change code owners to maintainers.

By submitting this pull request, I confirm that you can use, modify,
copy, and redistribute this contribution, under the terms of your
choice.

Author: pxaws

.github/CODEOWNERS

@@ -2,4 +2,4 @@
 #  https://help.github.com/en/articles/about-code-owners
 
 # Default owners for the entire repo
-* @aws-observability/aws-application-signals-team
+* @aws-observability/aws-application-signals-maintainers