[OWNERS] Update OWNERS file

Adding myself and jruthe, who plan to work on this repo actively.
Removing folks who have not made changes in this repo for some time.

Change-Id: I289cb77ebb18955c4d53e2ec8c46c96bb1e1b13c
Reviewed-on: https://fuchsia-review.googlesource.com/c/vscode-plugins/+/1028512
Reviewed-by: Jacob Rutherford <jruthe@google.com>
Kokoro: Kokoro <noreply+kokoro@google.com>
Reviewed-by: Clayton Wilkinson <wilkinsonclay@google.com>
diff --git a/OWNERS b/OWNERS
index d6928e7..2fa9f5c 100644
--- a/OWNERS
+++ b/OWNERS
@@ -1,4 +1,3 @@
+abarth@google.com
+jruthe@google.com
 wilkinsonclay@google.com
-mgnb@google.com
-slgrady@google.com
-colnnelson@google.com