3.12.6 release notes

(cherry picked from commit b08dd15)

release-notes/3.12.5.md

@@ -1,5 +1,5 @@
-
 RabbitMQ `3.12.5` is a maintenance release in the `3.12.x` [release series](https://www.rabbitmq.com/versions.html).
+**All users are encouraged to skip this version in favor of [`3.12.6`](https://github.com/rabbitmq/rabbitmq-server/releases/tag/v3.12.6)**.
 
 Please refer to the upgrade section from the [3.12.0 release notes](https://github.com/rabbitmq/rabbitmq-server/releases/tag/v3.12.0)
 if upgrading from a version prior to 3.12.0.

release-notes/3.12.6.md

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+RabbitMQ `3.12.6` is a maintenance release in the `3.12.x` [release series](https://www.rabbitmq.com/versions.html).
+
+Please refer to the upgrade section from the [3.12.0 release notes](https://github.com/rabbitmq/rabbitmq-server/releases/tag/v3.12.0)
+if upgrading from a version prior to 3.12.0.
+
+This release requires Erlang 25 and supports Erlang versions up to `26.0.x`.
+[RabbitMQ and Erlang/OTP Compatibility Matrix](https://www.rabbitmq.com/which-erlang.html) has more details on
+Erlang version requirements for RabbitMQ.
+
+
+### Minimum Supported Erlang Version
+
+As of 3.12.0, RabbitMQ requires Erlang 25. Nodes **will fail to start** on older Erlang releases.
+
+Users upgrading from 3.11.x (or older releases) on Erlang 25 to 3.12.x on Erlang 26
+(both RabbitMQ *and* Erlang are upgraded at the same time) **must** consult
+the [v3.12.0 release notes](https://github.com/rabbitmq/rabbitmq-server/releases/tag/v3.12.0) first.
+
+
+## Changes Worth Mentioning
+
+Release notes can be found on GitHub at [rabbitmq-server/release-notes](https://github.com/rabbitmq/rabbitmq-server/tree/v3.12.x/release-notes).
+
+
+### Core Server
+
+#### Bug Fixes
+
+ * `3.12.5` unintentionally shipped with a `seshat` version older than `0.6.1`. This can potentially
+   result in an incompatibility with the stream subsystem.
+
+   GitHub issue: [#9499](https://github.com/rabbitmq/rabbitmq-server/pull/9499)
+
+#### Enhancements
+
+ * Improved forward compatibility of classic queues with 3.13.
+
+   GitHub issue: [#9508](https://github.com/rabbitmq/rabbitmq-server/pull/9508)
+
+
+## Dependency Upgrades
+
+ * `seshat` was upgraded to [`0.6.1`](https://github.com/rabbitmq/seshat/tags)
+
+
+## Dependency Upgrades
+
+None in this release.
+
+## Source Code Archives
+
+To obtain source code of the entire distribution, please download the archive named `rabbitmq-server-3.12.6.tar.xz`
+instead of the source tarball produced by GitHub.