Add testing for PY311

[Carlton Gibson]

Adding testing agains PY311 beta:

---
 .github/workflows/tests.yml | 2 +-
 tox.ini                     | 1 +
 2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index 9d27ea3..f3a2895 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -13,7 +13,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        python-version: ["3.7", "3.8", "3.9", "3.10"]
+        python-version: ["3.7", "3.8", "3.9", "3.10", "3.11-dev"]
 
     steps:
       - uses: actions/checkout@v2
diff --git a/tox.ini b/tox.ini
index 3898a87..abd8a7c 100644
--- a/tox.ini
+++ b/tox.ini
@@ -2,6 +2,7 @@
 envlist =
        {py37,py38,py39,py310}-django32,
        {py38,py39,py310}-{django40,latest},
+       py311-{django41,latest},
        isort,lint,docs,warnings,
 
 
-- 
2.31.1

Errors installing lxml.

Collecting lxml
[37](https://github.com/carltongibson/django-filter/runs/6921460430?check_suite_focus=true#step:5:38)
  Downloading lxml-4.9.0.tar.gz (3.4 MB)
[38](https://github.com/carltongibson/django-filter/runs/6921460430?check_suite_focus=true#step:5:39)
     ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ 3.4/3.4 MB 132.5 MB/s eta 0:00:00
[39](https://github.com/carltongibson/django-filter/runs/6921460430?check_suite_focus=true#step:5:40)
  Preparing metadata (setup.py): started
[40](https://github.com/carltongibson/django-filter/runs/6921460430?check_suite_focus=true#step:5:41)
  Preparing metadata (setup.py): finished with status 'error'
[41](https://github.com/carltongibson/django-filter/runs/6921460430?check_suite_focus=true#step:5:42)
  error: subprocess-exited-with-error
[42](https://github.com/carltongibson/django-filter/runs/6921460430?check_suite_focus=true#step:5:43)
[43](https://github.com/carltongibson/django-filter/runs/6921460430?check_suite_focus=true#step:5:44)
  × python setup.py egg_info did not run successfully.
[44](https://github.com/carltongibson/django-filter/runs/6921460430?check_suite_focus=true#step:5:45)
  │ exit code: 1
[45](https://github.com/carltongibson/django-filter/runs/6921460430?check_suite_focus=true#step:5:46)
  ╰─> [3 lines of output]
[46](https://github.com/carltongibson/django-filter/runs/6921460430?check_suite_focus=true#step:5:47)
      Building lxml version 4.9.0.
[47](https://github.com/carltongibson/django-filter/runs/6921460430?check_suite_focus=true#step:5:48)
      Building without Cython.

Look into and resolve.

(Likely just works by final release.)

[Carlton Gibson]

Closed in fb5485e