lesspipe: Allow zstd to operate on a symlink

[emaste]

Summary

By default zstd refuses to operate on symlinks, so for example
`zless /var/crash/vmcore.last.zst` failed to view the uncompressed core
file.  Add -f to the zstd command line to allow operation on symlinks.

[delphij]

I'd probably use zstdcat -q here but change LGTM as-is too.

[emaste]

Ok - I went with the current version as I've been testing with it for a while, but have staged a switch to zstdcat in my local tree since I think it clearly matches our intention.