Export fails when layout name contains slash

[buttercookie42]

Describe the bug
If a layout name happens to contain a slash, the export fails.

To Reproduce
Steps to reproduce the behavior:

1. Create a layout with a slash in its name, e.g. "Exampletown North/South-Link".
2. Try exporting the layout via Maps Printer.
3. It fails.

Expected behavior
The layout is exported, any characters in the layout title that are illegal for file names (at the very least the path separator, on Windows the full complement of illegal characters seems to be \ / : ? " < > |) are replaced by some suitable substitute. If I try exporting that layout directly via QGIS's built-in export, the proposed default filename replaces the slash with an underscore, Maps Printer should do something similar.

Screenshots
If applicable, add screenshots to help explain your problem.

Desktop (please complete the following information):

• QGIS version: 3.10.7-A Coruña
• OS: Windows 10
• Maps Printer Version 0.8