Bump pixelmatch from 5.2.0 to 5.2.1
Bump pixelmatch from 5.2.0 to 5.2.1

Bumps [pixelmatch](https://github.com/mapbox/pixelmatch) from 5.2.0 to 5.2.1.
- [Release notes](https://github.com/mapbox/pixelmatch/releases)
- [Commits](https://github.com/mapbox/pixelmatch/compare/v5.2.0...v5.2.1)

Signed-off-by: dependabot-preview[bot] <5bdcd3c0d4d24ae3e71b3b452a024c6324c7e4bb@dependabot.com>
oterral/ol3,oterral/ol3,ahocevar/ol3,ahocevar/ol3,ahocevar/ol3,stweil/ol3,ahocevar/openlayers,ahocevar/ol3,stweil/ol3,adube/ol3,stweil/openlayers,openlayers/openlayers,adube/ol3,stweil/openlayers,stweil/ol3,bjornharrtell/ol3,stweil/ol3,oterral/ol3,openlayers/openlayers,stweil/openlayers,bjornharrtell/ol3,ahocevar/openlayers,openlayers/openlayers,ahocevar/openlayers,adube/ol3,bjornharrtell/ol3