Update sphinx-copybutton requirement from ~=0.3.3 to ~=0.4.0 (#80)

dependabot[bot] · web-flow · commit f15745f5e694 · 2021-08-01T08:51:54.000-07:00
diff --git a/requirements-dev.txt b/requirements-dev.txt
@@ -13,5 +13,5 @@ pytest ~=6.2.4
 ipython ~=7.25.0
 numpydoc ~=1.1.0
 sphinx ~=4.1.2
-sphinx-copybutton ~=0.3.3
+sphinx-copybutton ~=0.4.0
 sphinx_rtd_theme ~=0.5.2
