Fix dev link script on Windows

Symlinks prevent .rpyc files from being created. Hard links solve the problem on Windows. The problem persists on Linux, but fixing it on one platform is better than nothing in the short term.

I plan to universally solve this by replacing the link script with something better (a watch service or something).

Example error on Linux:

Full traceback:
  File "/home/khanfluence/mgd-ptce/MonGirlDreams/renpy/bootstrap.py", line 359, in bootstrap
    renpy.main.main()
  File "/home/khanfluence/mgd-ptce/MonGirlDreams/renpy/main.py", line 470, in main
    renpy.game.script.load_script() # sets renpy.game.script.
  File "/home/khanfluence/mgd-ptce/MonGirlDreams/renpy/script.py", line 359, in load_script
    self.load_appropriate_file(".rpyc", [ "_ren.py", ".rpy" ], dir, fn, initcode)
  File "/home/khanfluence/mgd-ptce/MonGirlDreams/renpy/script.py", line 949, in load_appropriate_file
    raise Exception("Could not load file %s." % lastfn) # type: ignore
UnboundLocalError: local variable 'lastfn' referenced before assignment

Relates to #1.