Function level `runtime` parameter does not work.

[privatejava]

Describe the bug
Currently, I started a simple serverless project that contains the runtime: node20.x trying to deploy for AWS. But it only works if the runtime is defined in the provider level. If I use it in the function level only then it fails.

To Reproduce
Set runtime: nodejs20.x at function level only and remove runtime from provider.

Then Run sls package

Expected behavior
It should work in any level of runtime definition.

Screenshots or Logs

Versions (please complete the following information):

• OS: Linux , Ubuntu 22.04
• Serverless Framework Version: 3.39.0
• Plugin Version: 1.52.1