Update pytest requirement from ~=6.0.1 to ~=6.1.0 (#637)

Updates the requirements on [pytest](https://github.com/pytest-dev/pytest) to permit the latest version.
- [Release notes](https://github.com/pytest-dev/pytest/releases)
- [Changelog](https://github.com/pytest-dev/pytest/blob/master/CHANGELOG.rst)
- [Commits](pytest-dev/pytest@6.0.1...6.1.0)

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

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

requirements-dev.txt

@@ -1,7 +1,7 @@
 coverage ~=5.2
 doctr ~=1.8.0
 pyflakes ~=2.2.0
-pytest ~=6.0.1
+pytest ~=6.1.0
 vcrpy ~=4.1.0
 doctr ~=1.8.0
 ipython ~=7.18.1