[pre-commit.ci] pre-commit autoupdate

[pre-commit-ci[bot]]

updates:

• https://github.com/ikamensh/flynt/: 0.78 → 1.0.0
• github.com/psf/black: 23.3.0 → 23.7.0

[ERosendo]

@mlissner I think We can merge this PR. I updated the test assets because the thumbnails created with the newest version of the pdftoppm command have a different binary representation and that was the reason tests were failing.

I checked the thumbnails, They look the same and have the same dimensions.

[mlissner]

LGTM.