Bump twilio from 6.30.0 to 7.15.1

Bumps [twilio](https://github.com/twilio/twilio-python) from 6.30.0 to 7.15.1.
- [Release notes](https://github.com/twilio/twilio-python/releases)
- [Changelog](https://github.com/twilio/twilio-python/blob/main/CHANGES.md)
- [Upgrade guide](https://github.com/twilio/twilio-python/blob/main/UPGRADE.md)
- [Commits](twilio/twilio-python@6.30.0...7.15.1)

---
updated-dependencies:
- dependency-name: twilio
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>

requirements.txt

@@ -1,7 +1,7 @@
 # Requirements for server-notifications-django
 
 Django==3.2.0
-twilio==6.30.0
+twilio==7.15.1
 python-dotenv==0.10.3
 
 # Production dependencies