severity level returned by custom function is not taking into account

[fmazeiras]

Describe the bug
severity displayed into the output should take into account severity returned by custom function

To Reproduce

1. using the following swagger petstore-openapi.json

2. using the spectral rule
   formats: ["oas3","oas2"]
   functions: [serverUrl]
   rules:
   OAPI-U1-server-dns-oas3:
   description: The service server is available via a DNS name
   message: '{{description}}. {{error}}'
   severity: error
   given: "$.servers[*]"
   formats: [oas3]
   then:
   function: serverUrl
   functionOptions:
   test: OAPIU1

3. with the following custom function
   serverUrl.js.txt

4. Run this CLI command 'spectral lint petstore-openapi.json --format json --ruleset spectral.yaml'

5. See error
   

Expected behavior
severity displayed into the output should take into account severity returned by custom function

Screenshots
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Environment (remove any that are not applicable):

• Library version: 6.11.1
• OS: Windows 11

Additional context
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