Exclude monoengine tests

 flask_admin/tests/mongoengine/conftest.py:4: in <module>
    from flask_mongoengine import MongoEngine
.tox/py312-flask3-wtforms3/lib/python3.12/site-packages/flask_mongoengine/__init__.py:10: in <module>
    from .json import override_json_encoder
.tox/py312-flask3-wtforms3/lib/python3.12/site-packages/flask_mongoengine/json.py:2: in <module>
    from flask.json import JSONEncoder
E   ImportError: cannot import name 'JSONEncoder' from 'flask.json' (/home/runner/work/flask-admin/flask-admin/.tox/py312-flask3-wtforms3/lib/python3.12/site-packages/flask/json/__init__.py)

tox.ini

@@ -25,12 +25,12 @@ deps =
     wtforms1: WTForms==1.0.5
     wtforms2: WTForms>=2.0,<3
     wtforms3: WTForms>=3.0,<4
-commands = pytest -v --tb=short --basetemp={envtmpdir} flask_admin/tests {posargs}
+commands = pytest -v --tb=short --basetemp={envtmpdir} flask_admin/tests {posargs} --ignore=flask_admin/tests/mongoengine/
 
 [testenv:py312-flask2-wtforms2-no-flask-babel]
 commands =
     pip uninstall -y flask-babel
-    pytest -v --tb=short --basetemp={envtmpdir} flask_admin/tests {posargs}
+    pytest -v --tb=short --basetemp={envtmpdir} flask_admin/tests {posargs} --ignore=flask_admin/tests/mongoengine/
 
 [testenv:style]
 deps = pre-commit