devel/py-watchdog: Update to 0.10.6

On Github, there is already v2.0.2, but from v1.0.0 on 'make test'
produces many errors for functions, which passes fine until <= v1.0.0.
Newer tests run with an update of devel/py-pytest >= v5.0.0 [1][2].

[1] https://docs.pytest.org/en/latest/changelog.html?highlight=pytestunknownmarkwarning
[2] https://github.com/pytest-dev/pytest/pull/5416

Changelog: https://github.com/gorakhargosh/watchdog/releases/tag/v0.10.6

PR: 244031
Submitted by: Evilham <contact@evilham.com>
Approved by: Nicola Vitale <nivit@FreeBSD.org> (maintainer timeout)
MFH: 2021Q1 (bugfixes)
Differential Revision: https://reviews.freebsd.org/D23608