[stubsabot] Bump flake8-2020 to 1.8.* (python#10153)

Release: https://pypi.org/pypi/flake8-2020/1.8.0
Homepage: https://github.com/asottile/flake8-2020
Diff: asottile-archive/flake8-2020@v1.7.0...v1.8.0

Stubsabot analysis of the diff between the two releases:
 - 0 public Python files have been added.
 - 0 files included in typeshed's stubs have been deleted.
 - 1 file included in typeshed's stubs has been modified or renamed: `flake8_2020.py`.
 - Total lines of Python code added: 9.
 - Total lines of Python code deleted: 7.

stubs/flake8-2020/METADATA.toml

@@ -1 +1 @@
-version = "1.7.*"
+version = "1.8.*"