Bump reorder-python-imports from 2.3.6 to 3.15.0 in /.github/workflows

Bumps [reorder-python-imports](https://github.com/asottile/reorder-python-imports) from 2.3.6 to 3.15.0.
- [Commits](asottile/reorder-python-imports@v2.3.6...v3.15.0)

---
updated-dependencies:
- dependency-name: reorder-python-imports
  dependency-version: 3.15.0
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

Author: dependabot[bot]

.github/workflows/constraints.txt

@@ -2,4 +2,4 @@ pip==21.0
 pre-commit==2.9.3
 black==20.8b1
 flake8==3.8.4
-reorder-python-imports==2.3.6
+reorder-python-imports==3.15.0