Release the PyGobject pin, documenting the consequences of that change. (#3256)

Author: freakboy3742

.github/workflows/ci.yml

@@ -242,7 +242,7 @@ jobs:
           pre-command: |
             sudo apt update -y
             sudo apt install -y --no-install-recommends \
-              blackbox pkg-config python3-dev libgirepository1.0-dev libcairo2-dev \
+              blackbox pkg-config python3-dev libgirepository-2.0-dev libcairo2-dev \
               gir1.2-webkit2-4.1 gir1.2-xapp-1.0 gir1.2-geoclue-2.0 gir1.2-flatpak-1.0
 
             # Start Virtual X Server
@@ -266,7 +266,7 @@ jobs:
           pre-command: |
             sudo apt update -y
             sudo apt install -y --no-install-recommends \
-              mutter pkg-config python3-dev libgirepository1.0-dev libcairo2-dev \
+              mutter pkg-config python3-dev libgirepository-2.0-dev libcairo2-dev \
               gir1.2-webkit2-4.1 gir1.2-xapp-1.0 gir1.2-geoclue-2.0 gir1.2-flatpak-1.0
 
             # Start Virtual X Server
@@ -290,12 +290,14 @@ jobs:
           runs-on: "ubuntu-24.04"
           env:
             XDG_RUNTIME_DIR: "/tmp"
-          # The package list should be the same as in unix-prerequisites.rst, and the BeeWare
-          # tutorial, plus mutter to provide a window manager.
+          # The package list should be build on the same base as unix-prerequisites.rst,
+          # and the BeeWare tutorial. Additional packages will be added for window
+          # management, and features such as web views and geolocation that aren't part
+          # of the default/tutorial environment.
           pre-command: |
             sudo apt update -y
             sudo apt install -y --no-install-recommends \
-              mutter pkg-config python3-dev libgirepository1.0-dev libcairo2-dev \
+              mutter pkg-config python3-dev libgirepository-2.0-dev libcairo2-dev \
               gir1.2-webkit-6.0 gir1.2-xapp-1.0 gir1.2-geoclue-2.0 gir1.2-flatpak-1.0 \
               gir1.2-gtk-4.0
 

changes/3143.bugfix.rst

@@ -0,0 +1 @@
+The binary dependencies for the GTK backend have been updated to reflect changes in requirements of PyGObject.

changes/3143.removal.rst

@@ -0,0 +1 @@
+If you're running on Ubuntu 22.04, Debian 11 or Debian 12, you'll need to manually add a pin for ``PyGObject==3.50.0`` to your project. This is because recent PyGObject releases specify a requirement on ``girepository-2.0``, which is not available on older Debian-based distributions. A manual pin is required because there's no way to express a dependency on a system package as part of Python's requirements specifications.

docs/reference/platforms/unix-prerequisites.rst

@@ -3,15 +3,27 @@ some of the common alternatives:
 
 ..
     The package list should be the same as in ci.yml, and the BeeWare tutorial
-    (CI will also have WebView requirements)
+    (CI will also have WebView and other requirements)
 
-**Ubuntu / Debian**
+**Ubuntu 24.04+ / Debian 13+**
+
+.. code-block:: console
+
+    (venv) $ sudo apt update
+    (venv) $ sudo apt install git build-essential pkg-config python3-dev libgirepository-2.0-dev libcairo2-dev gir1.2-gtk-3.0 libcanberra-gtk3-module
+
+**Ubuntu 22.04 / Debian 11, 12**
 
 .. code-block:: console
 
     (venv) $ sudo apt update
     (venv) $ sudo apt install git build-essential pkg-config python3-dev libgirepository1.0-dev libcairo2-dev gir1.2-gtk-3.0 libcanberra-gtk3-module
 
+If you're running on Ubuntu 22.04, Debian 11 or Debian 12, you'll also need add a pin
+for ``PyGObject==3.50.0``. Later versions of PyGObject require the
+``libgirepository-2.0-dev`` library, which isn't available on older Debian-based
+distributions.
+
 **Fedora**
 
 .. code-block:: console

gtk/pyproject.toml

@@ -64,14 +64,8 @@ root = ".."
 [tool.setuptools_dynamic_dependencies]
 dependencies = [
     "pycairo >= 1.17.0",
-    # TODO: PyGObject 3.50.0 is the first version with native GTK asyncio integration;
-    # PyGObject 3.51.0 will introduce a dependency on libgirepository-2.0, which isn't
-    # available on Ubuntu 22.04 and earlier. We need to make a bunch of other CI and
-    # documentation changes to accommodate this. Preemptively protect against the future
-    # release of 3.51.0, and the 3.51.0.dev0 pre-release that has been published to
-    # PyPI, but has inconsistent metadata and can't be installed with pip. See #3143.
-    # "pygobject >= 3.50.0",
-    "pygobject == 3.50.0",
+    # PyGObject 3.50.0 is the first version with native GTK asyncio integration.
+    "pygobject >= 3.50.0",
     "toga-core == {version}",
 ]