maint: don't regenerate rockspecs for announcement.
maint: don't regenerate rockspecs for announcement.

We don't want the `GEN foo.rockspec` lines in the announcement
message.
* build-aux/release.mk (announcement): Remove rockspec dependency.

Signed-off-by: Gary V. Vaughan <f9023000f29773649f3850298becb9544b5fd6a9@gnu.org>

gvvaughan/slingshot