unix/.gitignore: Remove *.py from ignore list.

.py files are valid source files and shouldn't be ignored.  This line was
from the early days when .py files in the unix directory were used for
testing.

Signed-off-by: Damien George <damien@micropython.org>

ports/unix/.gitignore

@@ -1,4 +1,3 @@
 micropython
 micropython-*
-*.py
 *.gcov