Revert "licenses: add gliderlabs/ssh license"

The gliderlabs/ssh license is actually already included in the standard
package listing.  I'm not sure why I thought it wasn't.

Updates tailscale/corp#5780

This reverts commit 11dca08e93.

Signed-off-by: Will Norris <will@tailscale.com>
This commit is contained in:
Internal Server Error - Gitea: Git with a cup of tea
500 Internal Server Error

Gitea Version: 1.28.0+dev-477-g8b6ad49a5f