py-numpy: updated to 1.16.4

1.16.4:
BUG: Some PyPy versions lack PyStructSequence_InitType2.
MAINT, DEP: Fix deprecated ``assertEquals()``
BUG: Fix structured_to_unstructured on single-field types (backport)
BLD: Make CI pass again with pytest 4.5
TST: Register markers in conftest.py.
BUG: Removes ValueError for empty kwargs in arraymultiter_new
BUG: Add TypeError to accepted exceptions in crackfortran.
BUG: Handle subarrays in descr_to_dtype
BUG: Protect generators from log(0.0)
BUG: Always return views from structured_to_unstructured when...
BUG: Catch stderr when checking compiler version
BUG: longdouble(int) does not work
BUG: distutils/system_info.py fix missing subprocess import
BUG,DEP: Fix writeable flag setting for arrays without base
MAINT: Prepare for the 1.16.4 release.
BUG: special case object arrays when printing rel-, abs-error

(adam)