Django-sendgrid-v5

What's Changed
* Support EU region endpoint by mikemanger in https://github.com/sklarsa/django-sendgrid-v5/pull/131
* Various pipeline and housekeeping tasks performed by mikemanger

New Contributors
* mikemanger made their first contribution in https://github.com/sklarsa/django-sendgrid-v5/pull/130

**Full Changelog**: https://github.com/sklarsa/django-sendgrid-v5/compare/v1.2.3...v1.2.4

What's Changed
* Adds reply_to_list by sklarsa in https://github.com/sklarsa/django-sendgrid-v5/pull/121


**Full Changelog**: https://github.com/sklarsa/django-sendgrid-v5/compare/v1.2.2...v1.2.3

Fix 114

Adds attachment content-type method handling (103)
Adds configurable tracking per-email (101)

Adds Django 3.2+ & 4.0 compatibility

Closes https://github.com/sklarsa/django-sendgrid-v5/issues/99

Personalization Fixes:
- _build_sg_personalization "to" arg now changed to optional; either it or existing_personalizations must be set.
- Prevent using .personalizations without tos set.
- Prevent unnecessary resetting of tos when personalization is already constructed.
- No longer provide tos if not set for personalizations. This is to prevent every personalization from being sent to every recipient in msg.to
- Added/Changed some comments/docstrings to reduce ambiguity

Thanks alichass for the contribution!