fix(petstore): Set to correct api url (OAI#3145)

* fix(petstore): Set to correct api url

Petstore api is now listening at: https://petstore.swagger.io/

* Update examples/v3.0/petstore-expanded.yaml

Co-authored-by: Mike Ralphson <[email protected]>

---------

Co-authored-by: Mike Ralphson <[email protected]>

Author: xorima

examples/v3.0/petstore-expanded.yaml

@@ -12,7 +12,7 @@ info:
     name: Apache 2.0
     url: https://www.apache.org/licenses/LICENSE-2.0.html
 servers:
-  - url: http://petstore.swagger.io/api
+  - url: https://petstore.swagger.io/v2
 paths:
   /pets:
     get: