Bump mock from 3.0.5 to 4.0.1 (#583)

Bumps [mock](https://github.com/testing-cabal/mock) from 3.0.5 to 4.0.1.
- [Release notes](https://github.com/testing-cabal/mock/releases)
- [Changelog](https://github.com/testing-cabal/mock/blob/master/CHANGELOG.rst)
- [Commits](testing-cabal/mock@3.0.5...4.0.1)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

requirements.txt

@@ -273,9 +273,9 @@ markupsafe==1.1.1 \
     --hash=sha256:c8716a48d94b06bb3b2524c2b77e055fb313aeb4ea620c8dd03a105574ba704f \
     --hash=sha256:cd5df75523866410809ca100dc9681e301e3c27567cf498077e8551b6d20e42f \
     --hash=sha256:e249096428b3ae81b08327a63a485ad0878de3fb939049038579ac0ef61e17e7
-mock==3.0.5 \
-    --hash=sha256:83657d894c90d5681d62155c82bda9c1187827525880eda8ff5df4ec813437c3 \
-    --hash=sha256:d157e52d4e5b938c550f39eb2fd15610db062441a9c2747d3dbfa9298211d0f8
+mock==4.0.1 \
+    --hash=sha256:2a572b715f09dd2f0a583d8aeb5bb67d7ed7a8fd31d193cf1227a99c16a67bc3 \
+    --hash=sha256:5e48d216809f6f393987ed56920305d8f3c647e6ed35407c1ff2ecb88a9e1151
 more-itertools==8.2.0 \
     --hash=sha256:5dd8bcf33e5f9513ffa06d5ad33d78f31e1931ac9a18f33d37e77a180d393a7c \
     --hash=sha256:b1ddb932186d8a6ac451e1d95844b382f55e12686d51ca0c68b6f61f2ab7a507