Pin pylint-django to 2.5.4

v2.5.5 switches to pylint 3.x which errors out with:

File "/home/runner/work/trackers-integration/Kiwi/kiwi_lint/dunder_attributes.py", line 11, in DunderClassAttributeChecker
    __implements__ = (interfaces.IAstroidChecker,)
AttributeError: module 'pylint.interfaces' has no attribute 'IAstroidChecker'

requirements/readthedocs.txt

@@ -12,6 +12,6 @@ factory_boy
 mock
 pydot
 # linting tools
-pylint-django
+pylint-django==2.5.4
 twine
 pyOpenSSL