fix: always use forward slashes in glob pattern

[cyyynthia]

This fixes an incompatibility with Windows systems, where the glob pattern would contain backward slashes due to the use of path.join.

[mheap]

@cyyynthia Could you share the sample output that you see on Windows? I'd expect backslashes to be used here as it's a directory

[cyyynthia]

I don't have my machine around, but it basically just fails to find any yaml file whenever using a directory. Works fine when pointing at a yaml file directly.

Moreover, the fast-glob documentation is pretty clear on the fact that only forward slashes should be used even on Windows.

[cyyynthia]

The script simply fails saying Didn't find Y(A)ML files in provided paths: .github/workflows.

Here is the warning in the documentation I was referring to about forward vs backward slashes: https://github.com/mrmlnc/fast-glob#pattern-syntax