add dependabot and relevant workflow to update, approve and merge @seamapi/* dependencies

[kainpets]

I've setup this code inside a fork or seam-cli, secured the repo to require approval before merging, enabled dependabot version updates in repo settings, downgraded the @seamapi/http package to one of previous versions and got it to run successfully as seen below.

Please enable dependabot version updates as per this guide: https://docs.github.com/en/code-security/getting-started/dependabot-quickstart-guide#enabling-dependabot-for-your-repository

[kainpets]

The dependabot is also setup to scan and update all dependencies that look like '@seamapi/*'. LMK if we want to restrict the updates to just '@seamapi/http'

This is how it works on my fork