fix(tests): the parallel test runner works on Python 3.14; CI tests 3.14

Python 3.14 starts processes with forkserver, which Django 5.2's parallel
runner does not support: its workers import the tests before
django.setup() and fail (AppRegistryNotReady), and `--parallel` without a
number falls back to one process. The project's test runner sets the
start method to fork, as it was up to 3.13. The production image runs
Python 3.14 (Ubuntu 26.04): CI adds it, and the parallel run moves to that
leg.

Tried on Ubuntu 26.04's Python 3.14: `test --parallel 4` and `--parallel`
(8 processes) pass; before, both hung.

.github/workflows/test.yml

@@ -18,7 +18,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        python-version: ['3.10', '3.11', '3.12', '3.13']
+        python-version: ['3.10', '3.11', '3.12', '3.13', '3.14']
         database: [sqlite]
         include:
           - python-version: '3.12'
@@ -110,9 +110,10 @@ jobs:
           coverage run manage.py test
           coverage report --skip-covered
 
-      # The project test runner (webvirtcloud/test_runner.py) on one leg
+      # The project test runner (webvirtcloud/test_runner.py) on the Docker
+      # image's Python, whose default start method its workers need changed
       - name: Run Test Suite In Parallel
-        if: matrix.python-version == '3.13' && matrix.database == 'sqlite'
+        if: matrix.python-version == '3.14' && matrix.database == 'sqlite'
         run: python manage.py test --parallel
 
       # The per-file report of one leg, to see what a change left untested

README.md

@@ -1,5 +1,5 @@
 # WebVirtCloud
-###### Python >=3.10 & Django 5.2 LTS (tested on Python 3.10 – 3.13)
+###### Python >=3.10 & Django 5.2 LTS (tested on Python 3.10 – 3.14)
 
 WebVirtCloud is a **web visualization and management layer** for **libvirt**-based virtualization infrastructure.
 
@@ -65,7 +65,7 @@ WebVirtCloud and `virt-manager`/`virsh` can manage the same libvirt host **concu
 
 ## Installation
 
-The installer supports Ubuntu 22.04 / 24.04 / 26.04, Debian 12 / 13, RHEL / Rocky Linux / AlmaLinux / Oracle Linux 10, openEuler 24.03 LTS, openSUSE Leap 15.x / Tumbleweed and SLES 15; the panel runs on a virtual machine, a physical host or a KVM host itself and needs Python 3.10 or newer. CI tests Python 3.10–3.13 on Ubuntu (sqlite, and PostgreSQL on 3.12) and the Docker image; the distro installs are not tested in CI. Pick one of the three ways below, then do the [first login](#first-login).
+The installer supports Ubuntu 22.04 / 24.04 / 26.04, Debian 12 / 13, RHEL / Rocky Linux / AlmaLinux / Oracle Linux 10, openEuler 24.03 LTS, openSUSE Leap 15.x / Tumbleweed and SLES 15; the panel runs on a virtual machine, a physical host or a KVM host itself and needs Python 3.10 or newer. CI tests Python 3.10–3.14 on Ubuntu (sqlite, and PostgreSQL on 3.12) and the Docker image; the distro installs are not tested in CI. Pick one of the three ways below, then do the [first login](#first-login).
 
 ### Installer
 

webvirtcloud/test_runner.py

@@ -1,12 +1,24 @@
 """manage.py test --parallel on the SQLite database in WAL mode."""
 
 import contextlib
+import multiprocessing
 import os
 import secrets
 
 from django.db import connections
 from django.test.runner import DiscoverRunner
 
+# Python 3.14 starts processes with forkserver on Linux, which Django 5.2's
+# parallel runner does not support (a worker imports the tests before
+# django.setup(), and --parallel without a number falls back to one process):
+# fork there, as up to 3.13; macOS keeps spawn. Set on import: the command
+# resolves --parallel while it parses.
+if (
+    multiprocessing.get_start_method(allow_none=True) is None
+    and multiprocessing.get_all_start_methods()[0] == "forkserver"
+):
+    multiprocessing.set_start_method("fork")
+
 
 def remove_wal_files(name):
     """Django replaces a SQLite test database by its main file only. A run