Ignore B024 flake-bugbear warning

PyCQA/flake8-bugbear#278

setup.cfg

@@ -1,6 +1,10 @@
 [flake8]
 max-line-length = 99
-ignore = E731, E402, W504, N818
+ignore =
+    E402,  # module level import at file top. https://www.flake8rules.com/rules/E402.html
+    W504,  # line break after binary operator. https://www.flake8rules.com/rules/W504.html
+    N818,  # error suffix in exception names
+    B024   # abstract base class with no abstract methods. https://github.com/PyCQA/flake8-bugbear/issues/278
 
 [isort]
 line_length=99