Add myself to approvers (#8745)

I do not have a desire of titles but I am trying this to make the hours
I spent on the project worth them. I feel very bad when I have full
confidence about a PR and I have reviewed it but I cannot approve it.

Author: tengqm

OWNERS

@@ -1,7 +1,6 @@
 # Reviewers can /lgtm /approve but not sufficient for auto-merge without an
 # approver
 reviewers:
-- tengqm
 - zhangxiaoyu-zidif
 - xiangpengzhao
 # Approvers have all the ability of reviewers but their /approve makes
@@ -15,3 +14,4 @@ approvers:
 - zacharysarah
 - chenopis
 - mistyhacks
+- tengqm