task.bbclass: Drop deprecated class

Any users have had time to adapt to this change by now, drop the old class.

(From OE-Core rev: 9b64b68c93c71c503ef26fa440b974b82438dc88)

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/classes/task.bbclass

@@ -1,6 +0,0 @@
-python __anonymous() {
-    bb.warn("%s: task.bbclass is deprecated, please inherit packagegroup instead" % d.getVar("PN", True))
-}
-
-inherit packagegroup
-