Accessing file by file panel on Windows

**Bug**
Trying to open a file from the filesystem panel makes the app try to open the file in a linux path format e.g.

/C:\some\path\someFile.c

Obviously this fails but strangely accessing the file by letting the program execute into it works fine.

**To Reproduce**
Steps to reproduce the behavior:
1. Using version 0.13.2.2 on Windows 11 access the filesystem panel on the top-left side
2. Try to open any of the listed files

**Screenshots**

* OS: Win11
* gdbgui version (`gdbgui -v`): 0.13.2.2
* gdb version (`gdb -v`): 16.2
* browser [e.g. chrome, safari]: Chrome
* python packages (`pip freeze`): (None, used exe)