This release has a variety of smaller fixes and cleanups, plus one new opt-in new feature to ensure the SELinux labels for `/usr/etc` are the same as `/etc`, which is important for enabling "transient etc" with ostree.

* compose: Two minor cleanups by @cgwalters in https://github.com/coreos/rpm-ostree/pull/4629
* ci: Bump hardcoded Ignition version by @cgwalters in https://github.com/coreos/rpm-ostree/pull/4639
* deny: Add ring by @cgwalters in https://github.com/coreos/rpm-ostree/pull/4630
* packaging/rpm-ostree: update python3 macros and builddep by @jmarrero in https://github.com/coreos/rpm-ostree/pull/4641
* docs/handbook: Add more details about inactive overrides by @jlebon in https://github.com/coreos/rpm-ostree/pull/4642
* Bump to ostree-ext 0.12.3 by @cgwalters in https://github.com/coreos/rpm-ostree/pull/4665
* Hard require ostree 2023.7 by @cgwalters in https://github.com/coreos/rpm-ostree/pull/4672
* Ensure rofiles-fuse gets SIGTERM if we exit by @cgwalters in https://github.com/coreos/rpm-ostree/pull/4660
* ci/upgrade: disable `zincati.service` in config.bu by @HuijingHei in https://github.com/coreos/rpm-ostree/pull/4671
* build(deps): bump tracing from 0.1.37 to 0.1.40 by @dependabot in https://github.com/coreos/rpm-ostree/pull/4669
* treefile: Add option to label `/usr/etc` as `/etc` by @cgwalters in https://github.com/coreos/rpm-ostree/pull/4640
* libpriv/rpm-util: Query package repo checksum under lock by @jlebon in https://github.com/coreos/rpm-ostree/pull/4673

**Full Changelog**: https://github.com/coreos/rpm-ostree/compare/v2023.8...v2023.9