best_compression for zst filter should be increased from 19 to 22

[KBentley57]

zstd compression allows up to 22, instead of 19. Tested to be working when changed manually. The maximum compression level was changed from 19 in zstd version 0.8.1 ( facebook/zstd@be6180c ) in 2016, which practically nobody will be using at this point.

[okravets]

Created #137 for this

[rdoeffinger]

Commented on the pull request. Not sure there's really enough value in updating this to bother?