Bump pngjs from 5.0.0 to 6.0.0
Bump pngjs from 5.0.0 to 6.0.0

Bumps [pngjs](https://github.com/lukeapage/pngjs) from 5.0.0 to 6.0.0.
- [Release notes](https://github.com/lukeapage/pngjs/releases)
- [Commits](https://github.com/lukeapage/pngjs/commits)

Signed-off-by: dependabot[bot] <5bdcd3c0d4d24ae3e71b3b452a024c6324c7e4bb@github.com>
SuperMap/iClient9,SuperMap/iClient9