bump version for bugfix release

pin version of isort used by pylint

allow misformatted dates in vendor reports in one more place

skip testing on nightly; it's Too Soon for py3.9

api_key support for COUNTER 5.

fix #96

document (deprecated) year property

Merge pull request #89 from beda42/master

fix error in totals computation with sparse data

pin pendulum to a version that will install on Windows.

Should be unpinned if python-pendulum/pendulum#365
is ever fixed, but right now pycounter won't install cleanly on
Windows (including on Appveyor) or anywhere the locale isn't set to
use UTF-8.

include a kludgy metric on COUNTER 5 SUSHI reports for compatibility

(This resolves a Pitt HSLS-specific blocker on bringing data from
COUNTER 5 SUSHI requests into our ERM in a compatible way, but
is far from ideal in a pure COUNTER 5 report. I suspect all
of the classes in the pycounter.report module will need to be
completely redesigned with a separate compatibility layer,
possibly outside of pycounter itself.)

Merge pull request #78 from Wooble/counter5_wip

Counter5 wip