add linting stubs with flake8-pyi and check for unused imports (#186)

django-stubs/contrib/admin/checks.pyi

@@ -1,6 +1,6 @@
 from typing import Any, List, Union
 
-from django.contrib.admin.options import BaseModelAdmin, InlineModelAdmin, ModelAdmin
+from django.contrib.admin.options import BaseModelAdmin
 from django.core.checks.messages import Error
 
 _CheckError = Union[str, Error]

django-stubs/contrib/admin/templatetags/admin_modify.pyi

@@ -1,7 +1,6 @@
-from typing import Any, Optional
+from typing import Any
 
 from django.contrib.admin.helpers import InlineAdminForm
-from django.contrib.admin.templatetags.base import InclusionAdminNode
 from django.template.base import Parser, Token
 from django.template.context import Context, RequestContext
 

django-stubs/contrib/admin/templatetags/admin_static.pyi

@@ -1,4 +1,4 @@
-from typing import Any, Optional
+from typing import Any
 
 register: Any
 

django-stubs/contrib/admin/views/main.pyi

@@ -2,7 +2,11 @@ from collections import OrderedDict
 from typing import Any, Callable, Dict, List, Optional, Tuple, Type, Union
 
 from django.contrib.admin.filters import ListFilter, SimpleListFilter
-from django.contrib.admin.options import ModelAdmin, IS_POPUP_VAR as IS_POPUP_VAR, TO_FIELD_VAR as TO_FIELD_VAR
+from django.contrib.admin.options import (  # noqa: F401
+    ModelAdmin,
+    IS_POPUP_VAR as IS_POPUP_VAR,
+    TO_FIELD_VAR as TO_FIELD_VAR,
+)
 from django.core.handlers.wsgi import WSGIRequest
 from django.db.models.base import Model
 from django.db.models.expressions import Combinable, CombinedExpression, OrderBy