argparse: Move back to python-stdlib.

Although this primarily makes sense for the unix port, there's nothing
preventing it being used on any port, and it's written for MicroPython.

Signed-off-by: Jim Mussared <jim.mussared@gmail.com>

unix-ffi/unittest/manifest.py

@@ -1,6 +1,6 @@
 metadata(version="0.9.0")
 
-require("argparse", unix_ffi=True)
+require("argparse")
 require("fnmatch")
 
 module("unittest.py")