Fix: Make swagger doc compliant to OpenAPI (#3394)

This fixes issues in the swagger.json file. The motivation to do so is to be able to generate API clients using https://openapi-generator.tech Doing so will require further changes to the api spec, but this seems like a good first step since it is now "valid" according to editor.swagger.io and openapi-generator validate.

Fixes #2806

swagger/paths/public/inboxes/contacts/create.yml

@@ -3,8 +3,7 @@ tags:
 operationId: create-a-contact
 summary: Create a contact
 description: Create a contact
-security:
-  - nil
+security: []
 parameters:
   - name: data
     in: body

swagger/paths/public/inboxes/contacts/show.yml

@@ -3,8 +3,7 @@ tags:
 operationId: get-details-of-a-contact
 summary: Get a contact
 description: Get the details of a contact
-security:
-  - nil
+security: []
 responses:
   200:
     description: Success

swagger/paths/public/inboxes/contacts/update.yml

@@ -3,8 +3,7 @@ tags:
 operationId: update-a-contact
 summary: Update a contact
 description: Update a contact's attributes
-security:
-  - nil
+security: []
 parameters:
   - name: data
     in: body