remove the unwanted extra newline added by sys.stdin

[PiRK]

When running flynt on stdin, there is an extra newline added to the input, which ends up in the output.

To reproduce the issue, run this before and after this commit (after writing some dummy code to in.py):

cat in.py  | flynt - > out.py
diff in.py out.py

The only diff should be the converted f-strings.

[PiRK]

I believe the fix to the pre-commit issue is https://github.com/ikamensh/flynt/pull/164/commits/b2e9d95541ef4a00d379c399b79897ec42fd0040

The issue should go away if this is rebased onto that commit.

[ikamensh]

I believe the fix to the pre-commit issue is b2e9d95

The issue should go away if this is rebased onto that commit.

Could you please rebase

[PiRK]

Could you please rebase

Done