Fix xlsx reader loading sheets with comments

[xklid101]

Fix #375

This is:

- [x] a bugfix
- [ ] a new feature

Checklist:

• Changes are covered by unit tests
• Code style is respected
• Commit message explains why the change is made (see https://github.com/erlang/otp/wiki/Writing-good-commit-messages)
• CHANGELOG.md contains a short summary of the change
• Documentation is updated as necessary

Why this change is needed?

When opening xlsx file that contains comments with xlsx reader, phpspreadsheet worksheet contains one more empty comment on left next every original comment

[PowerKiKi]

Similar comment than for the other PR, we should avoid relying on pre-existing file for tests to avoid repository size growth. Instead this test would probably be a good fit for a functional test (write and read for multiple formats). You'll find example on existing tests.

[xklid101]

Check my latest commits, I've done some changes. If anything else to be done, let mi know and I'll try to do it. Or post some comments... Thx