Pre-release checklist

[cleptric]

• Perform the Moving Github Repo to Public Checklist
• Add CI
• Submit to https://packagist.org/
• Add rate limiting
• Setup Craft
• Fix hard-coded COMPOSER_ROOT_VERSION (Reproducible builds #23)
• Fix box.json timestamp (Reproducible builds #23)
• Cleanup @TODO comments (Improve the CLI output and interactions #24, ...)
• Add profile rate-limit check (see: ref(rate-limit): handle profile and check_in rate limiting sentry-php#1970) not needed since we rate limit individual envelope items and profile is still a separate item in the envelope we can drop separately
• Fallback transport to allow the SDK to send to agent or fallback to direct (Allow setting a fallback transport to fall through to #15)
• Write tests
• Verify signature
• Write docs
• Add branch protection + auto delete merged branches