Bump pypng from 0.0.18 to 0.0.20
Bump pypng from 0.0.18 to 0.0.20

Bumps [pypng](https://github.com/drj11/pypng) from 0.0.18 to 0.0.20.
- [Release notes](https://github.com/drj11/pypng/releases)
- [Commits](https://github.com/drj11/pypng/compare/pypng-0.0.18...pypng-0.0.20)

Signed-off-by: dependabot-preview[bot] <5bdcd3c0d4d24ae3e71b3b452a024c6324c7e4bb@dependabot.com>
Dantistnfs/telegram-genetic-bot