Remove wave from requirements-dev.txt (#12387)

This resolves to <https://pypi.org/project/Wave/>, but the places where
the `wave` module is imported make it clear that the standard library
module <https://docs.python.org/3/library/wave.html> was intended.

Was originally added in #11820 and used in the following files:
* `util/sample_parser.py`
* `util/wavetable_parser.py`

requirements-dev.txt

@@ -6,4 +6,3 @@ nose2
 flake8
 pep8-naming
 yapf
-wave