fix deduplication by defining order in event_params

[FlorianASchroeder]

Description & motivation

resolves #258

Sort event_params by key for improved de-duplication.

Checklist

• [ ] I have verified that these changes work locally
• [ ] I have updated the README.md (if applicable)
• [ ] I have added tests & descriptions to my models (and macros if applicable)
• [ ] I have run dbt test and python -m pytest . to validate existing tests

[adamribaudo-velir]

Good catch, thanks.