Release v4.3-beta1 (#19172)

* Draft changelog for v4.3 release

* Add release notes summary & nav link

* Docs cleanup

* Update Python dependencies

* Update static assets

* Revert errant change to schema

* Fix minimum PostgreSQL version

* Misc cleanup

* Correct issue numbers in change log

docs/plugins/development/models.md

@@ -119,6 +119,8 @@ For more information about database migrations, see the [Django documentation](h
 
 ::: netbox.models.features.ContactsMixin
 
+!!! info "Plugin support for ContactsMixin was introduced in NetBox v4.3."
+
 ::: netbox.models.features.CustomLinksMixin
 
 ::: netbox.models.features.CustomFieldsMixin
@@ -127,9 +129,6 @@ For more information about database migrations, see the [Django documentation](h
 
 ::: netbox.models.features.EventRulesMixin
 
-!!! note
-    `EventRulesMixin` was renamed from `WebhooksMixin` in NetBox v3.7.
-
 ::: netbox.models.features.ExportTemplatesMixin
 
 ::: netbox.models.features.JobsMixin