Network drive support

Trying to run thonny-py5-mode on a file across a network fails. Note the `\\` prefix in the file path below, which should include a drive-letter, i.e. `D:\\`. Perhaps this is a problem for files on external/flash drives, too?
```
%Run 'C:\Users\<user>\AppData\Roaming\Python\Python38\site-packages\py5_tools\tools\run_sketch.py' '\\example.domain.location\<file_path>\file.py'
```
