[pre-commit.ci] pre-commit autoupdate (#85)

updates:
- [github.com/psf/black: 21.5b2 → 21.6b0](psf/black@21.5b2...21.6b0)

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

.pre-commit-config.yaml

@@ -17,7 +17,7 @@ repos:
         # Don't commit to master branch.
     -   id: no-commit-to-branch
 -   repo: https://github.com/psf/black
-    rev: '21.5b2'
+    rev: '21.6b0'
     hooks:
     -   id: black
         # Force black to run on whole repo, using settings from pyproject.toml