owners: promote tomasaschan to owner

tomasaschan · tomasaschan · commit 135b2b3432cc · 2024-05-23T11:41:24.000+02:00
This was discussed already in #381 but hasn't happened yet.
diff --git a/OWNERS b/OWNERS
@@ -4,6 +4,4 @@ approvers:
   - justinsb
   - johnsonj
   - atoato88
-
-reviewers:
-  - tomasaschan
+  - tomasaschan
