Change codeowners to be all memembers of @tensorflow/micro (#98)

diff --git a/CODEOWNERS b/CODEOWNERS
index 659a61f..1471d5d 100644
--- a/CODEOWNERS
+++ b/CODEOWNERS
@@ -1,4 +1,4 @@
-*          @advaitjain @njeffrie
+*          @tensorflow/micro
 
 /.github/  @advaitjain
 /ci/       @advaitjain