feat(developer): drop php 8.0

Signed-off-by: Richard Steinmetz <richard@steinmetz.cloud>

developer_manual/app_publishing_maintenance/app_upgrade_guide/index.rst

@@ -11,6 +11,7 @@ These sub pages will cover the most important changes in Nextcloud, as well as s
 .. toctree::
    :maxdepth: 1
 
+   upgrade_to_30.rst
    upgrade_to_29.rst
    upgrade_to_28.rst
    upgrade_to_27.rst

developer_manual/app_publishing_maintenance/app_upgrade_guide/upgrade_to_30.rst

@@ -0,0 +1,63 @@
+=======================
+Upgrade to Nextcloud 30
+=======================
+
+General
+-------
+
+Front-end changes
+-----------------
+
+Added APIs
+^^^^^^^^^^
+
+Changed APIs
+^^^^^^^^^^^^
+
+Removed APIs
+^^^^^^^^^^^^
+
+Removed globals
+^^^^^^^^^^^^^^^
+
+Back-end changes
+----------------
+
+Support for PHP 8.0 removed
+^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+In this release support for PHP 8.0 was removed. Follow the steps below to make your app compatible.
+
+1. If ``appinfo/info.xml`` has a dependency specification for PHP, increase the ``min-version`` to 8.1.
+
+.. code-block:: xml
+
+  <dependencies>
+    <php min-version="8.1" max-version="8.3" />
+    <nextcloud min-version="27" max-version="30" />
+  </dependencies>
+
+
+2. If your app has a ``composer.json`` and the file contains the PHP restrictions from ``info.xml``, adjust it as well.
+
+.. code-block:: json
+
+  {
+    "require": {
+      "php": ">=8.1 <=8.3"
+    }
+  }
+
+3. If you have :ref:`continuous integration <app-ci>` set up, remove PHP 8.0 from the matrices of tests and linters.
+
+Added APIs
+^^^^^^^^^^
+
+Changed APIs
+^^^^^^^^^^^^
+
+Removed APIs
+^^^^^^^^^^^^
+
+Removed events
+^^^^^^^^^^^^^^