remove approvals as no longer used

.zappr.yaml

 # for github.com
-approvals:
-  groups:
-    zalando:
-      minimum: 2
-      from:
-        orgs:
-          - "zalando"
 X-Zalando-Team: "acid"
 # type should be one of [code, doc, config, tools, secrets]
 # code will be the default value, if X-Zalando-Type is not found in .zappr.yml