Add lint dependencies to requirements file

Author: scottandee

messaging_app/requirements.txt

@@ -6,10 +6,14 @@ djangorestframework==3.16.1
 djangorestframework_simplejwt==5.5.1
 drf-nested-routers==0.95.0
 exceptiongroup==1.3.1
+flake8==7.3.0
 iniconfig==2.3.0
+mccabe==0.7.0
 mysqlclient==2.2.7
 packaging==25.0
 pluggy==1.6.0
+pycodestyle==2.14.0
+pyflakes==3.4.0
 Pygments==2.19.2
 PyJWT==2.10.1
 pytest==9.0.2