fix: Drop pypy 3.9 support

pypy 3.9 do not work with latest asgiref packages

Refs https://github.com/MongoEngine/django-mongoengine/actions/runs/12526370178/job/34938914923?pr=207

Author: last-partizan

.github/workflows/test.yml

@@ -18,7 +18,6 @@ jobs:
           - "3.11"
           - "3.12"
           - "3.13"
-          - "pypy3.9"
           - "pypy3.10"
         django:
           - "Django>=4.2,<4.3"
@@ -29,10 +28,6 @@ jobs:
             django: "Django>=5.0,<5.1"
           - python: "3.9"
             django: "Django>=5.1,<5.2"
-          - python: "pypy3.9"
-            django: "Django>=5.0,<5.1"
-          - python: "pypy3.9"
-            django: "Django>=5.1,<5.2"
     env:
       GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
       DJANGO: ${{ matrix.django }}