Update flake8 requirement from ~=3.9.2 to ~=4.0.1 (#87)

dependabot[bot] · web-flow · commit 150d3a1a4290 · 2021-11-01T07:02:56.000-07:00
diff --git a/requirements-dev.txt b/requirements-dev.txt
@@ -8,7 +8,7 @@
 # It only exists to keep the list of dependencies in a separate file from
 # setup.py.
 coverage ~=5.5
-flake8 ~=3.9.2
+flake8 ~=4.0.1
 pytest ~=6.2.5
 ipython ~=7.28.0
 numpydoc ~=1.1.0
