OWNERS: update Ratan email

Looking through the gerrit logs is difficult as it will log lots and
lots of these whenever a review in this repo is ongoing:

```
 WARN  com.googlesource.gerrit.owners.common.AccountsImpl :
 User 'ratagupt@linux.vnet.ibm.com' does not resolve to any account
```

Change-Id: Iea7e0756fa56194085c958fa368fa52607002319
Signed-off-by: Andrew Geissler <geissonator@yahoo.com>
diff --git a/OWNERS b/OWNERS
index 1a5d8d5..0d51557 100644
--- a/OWNERS
+++ b/OWNERS
@@ -39,7 +39,7 @@
 - anoo@us.ibm.com
 - deepak.kodihalli.83@gmail.com
 - liuxiwei@ieisystem.com
-- ratagupt@linux.vnet.ibm.com
+- ratankgupta31@gmail.com
 
 matchers:
 
@@ -54,7 +54,7 @@
   email: liuxiwei@ieisystem.com
   discord: George Liu
 - name: Ratan Gupta
-  email: ratagupt@linux.vnet.ibm.com
+  email: ratankgupta31@gmail.com
   discord: rgupta
 - name: Tom Joseph
   email: rushtotom@gmail.com