Remove unused launchpad key file

Commit d841da9379c7d08408c55bfa5d24276826362b23 removed
the dependency on libzfs-dev from the Dockerfile.

This key file was only used for the PPA used to
install libzfs-dev, and is now no longer
needed.

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

keys/launchpad-ppa-zfs.asc

@@ -1,13 +0,0 @@
------BEGIN PGP PUBLIC KEY BLOCK-----
-Version: GnuPG v1
-
-mI0ETjjRQwEEAN1t7LdXiXEDucAXemaXZphLeDSmUE2gHxj/b+Gqt1wRaCMAE1NU
-rLOqTDNq8XPi4ZSp8Rr8R8jVupmKlt446ESGOadUO0AAjFyYe+YwZ65uYa69536k
-T+PhcFepWm8YgJL1skn0u+qpHzMJLvLB6iyAP8fP5C19wjiY8TtpSEtLABEBAAG0
-JkxhdW5jaHBhZCBQUEEgZm9yIE5hdGl2ZSBaRlMgZm9yIExpbnV4iLgEEwECACIF
-Ak440UMCGwMGCwkIBwMCBhUIAgkKCwQWAgMBAh4BAheAAAoJEBGWuoH2sPxh32cD
-/2uniH9nyAKYI3/6X29pmRXcsuf1J+ZYqEnUIWT41ZBvNJHkbMiSgNC0lUvW4miq
-LgHZrft2X3D1fUP6djnueTnFG/Rs/uVRCMU32YjmxW92nZc6StfNt35LT7CUd9xV
-/6e3h5klln/xUsimOm9BcHglUXF7n8U39qw9JGV2sheo
-=qkiU
------END PGP PUBLIC KEY BLOCK-----