[pre-commit.ci] pre-commit autoupdate (#1012)

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

@@ -1,6 +1,6 @@
 repos:
   - repo: https://github.com/psf/black
-    rev: 21.5b2 # Replace by any tag/version: https://github.com/psf/black/tags
+    rev: 21.6b0 # Replace by any tag/version: https://github.com/psf/black/tags
     hooks:
       - id: black
         language_version: python3 # Should be a command that runs python3.6+