- Package requires pytest 4.x or newer

- Remove py2 dep as the package is marked as python3 only

- Update to 0.10.1
* Fixed bug introduced in 0.10 that prevented creation of size-zero Quantities
from NumPy arrays by multiplication.
* Fixed several Sphinx issues. Fixed intersphinx hooks to all classes missing.
* Fixed __array__ signature to match numpy docs
- Update to 0.10
* **BREAKING CHANGE**:
Boolean value of Quantities with offsets units is ambiguous, and so, now a ValueError
is raised when attempting to cast such a Quantity to boolean.
* **BREAKING CHANGE**:
`__array_ufunc__` has been implemented on `pint.Unit` to permit
multiplication/division by units on the right of ufunc-reliant array types (like
Sparse) with proper respect for the type casting hierarchy. However, until an
upstream issue with NumPy is resolved,
this breaks creation of Masked Array Quantities by multiplication on the right.
* Documentation on Pint's array type compatibility has been added to the NumPy support
page, including a graph of the duck array type casting hierarchy as understood by Pint
for N-dimensional arrays.
* Improved compatibility for downcast duck array types like Sparse.COO. A collection
of basic tests has been added.
* Improvements to wraps and check:
> fail upon decoration (not execution) by checking wrapped function signature against
wraps/check arguments.
(might BREAK test code)
> wraps only accepts strings and Units (not quantities) to avoid confusion with magnitude.
(might BREAK code not conforming to documentation)