Update extension.yaml

[charlie-topete]

Updated Node.js runtime to v20

[aTomSoftware]

This is a showstopper error, very urgent to fix, otherwise it cannot be deployed:

Error installing extension. Be aware that a parameter misconfiguration might have caused some to not successfully deploy.

; RESOURCE_ERROR at /deployments/firebase-ext-historian/resources/processEvent: {"ResourceType":"gcp-types/cloudfunctions-v1:projects.locations.functions","ResourceErrorCode":"400","ResourceErrorMessage":{"code":400,"message":"Failed to create 1st Gen function projects/**/locations//functions/ext-historian-processEvent: runtime: Runtime validation errors: [error_code: \t DEPLOYS_NOT_ALLOWED\nmessage: "Runtime nodejs18 is decommissioned and no longer allowed. Please use the latest Node.js runtime for Cloud Functions."\n]","status":"INVALID_ARGUMENT","statusMessage":"Bad Request","requestPath":"https://cloudfunctions.googleapis.com/v1/projects/*****/locations/***/functions","httpMethod":"POST"}}