Revert "remove versioning from HTML (UI) template views #1036"

Even though this change makes sense in principle,
it may be a regression and having the HTML views have versioning
classes does make sense in certain situations.
Revert the change as this is not a clear improvement on closer
inspection.

This reverts commit 388da8d.

drf_spectacular/views.py

@@ -122,7 +122,6 @@ class SpectacularSwaggerView(APIView):
     renderer_classes = [TemplateHTMLRenderer]
     permission_classes = spectacular_settings.SERVE_PERMISSIONS
     authentication_classes = AUTHENTICATION_CLASSES
-    versioning_class = None
     url_name = 'schema'
     url = None
     template_name = 'drf_spectacular/swagger_ui.html'
@@ -232,7 +231,6 @@ class SpectacularRedocView(APIView):
     renderer_classes = [TemplateHTMLRenderer]
     permission_classes = spectacular_settings.SERVE_PERMISSIONS
     authentication_classes = AUTHENTICATION_CLASSES
-    versioning_class = None
     url_name = 'schema'
     url = None
     template_name = 'drf_spectacular/redoc.html'