fix(openapi): use correct response type for key deletion (#77)

* fix response schema for DELETE /keys/{keyId} endpoint
* add missing ApiKeyDeleteResponse schema definition
* ensure id field description matches actual response

Author: tharropoulos

openapi.yml

@@ -1105,7 +1105,7 @@ paths:
           content:
             application/json:
               schema:
-                $ref: "#/components/schemas/ApiKey"
+                $ref: "#/components/schemas/ApiKeyDeleteResponse"
         400:
           description: Bad request, see error message for details
           content:
@@ -2363,6 +2363,15 @@ components:
             value_prefix:
               type: string
               readOnly: true
+    ApiKeyDeleteResponse:
+      type: object
+      required:
+        - id
+      properties:
+        id:
+          type: integer
+          format: int64
+          description: The id of the API key that was deleted
     ApiKeysResponse:
       type: object
       required: