Dep updates (pgx, dktest) (#956)

* Dep updates:

* pgx
* dktest

* Remove pgx

depowners.md

@@ -81,9 +81,6 @@ the first place.
     * Jeff
 * github.com/iancoleman/strcase
     * Jeff
-* github.com/jackc/pgx/v4
-    * Jim
-    * Mike
 * github.com/jefferai/keyring
     * Jeff
 * github.com/jinzhu/gorm
@@ -140,4 +137,4 @@ the first place.
     * Jeff
 * nhooyr.io/websocket
     * Jeff
-    * Jim
+    * Jim