Fix extra blank line after each code line on Windows

[Ky9oss]

This pull request addresses an issue with extra blank lines on Windows, which causes additional blank lines between code lines in IPython and the REPL of Python 3.13/3.14. Example:

Python 3.11.7 | packaged by Anaconda, Inc. | (main, Dec 15 2023, 18:05:47) [MSC v.1916 64 bit (AMD64)]
Type 'copyright', 'credits' or 'license' for more information
IPython 8.20.0 -- An enhanced Interactive Python. Type '?' for help.

In [1]: class MyClass:
   ...:
   ...:         def hello(self):
   ...:
   ...:                     print('hello python\n')
   ...:

In [2]:

In [2]:

In [2]:

In [2]: c = MyClass()

In [3]:

In [3]: c.hello()

The issue stems from vim.fn.chansend appending \r\n to each piece of data on Windows. In Python 3.13/3.14 and IPython, \r\n is interpreted as two line breaks instead of one, resulting in an extra blank line after each line of code.
To fix this, we manually join each piece of data with \r.