Remove duplicate tweetnacl license override

Author: Michelle Tilley

build/tasks/license-overrides.coffee

@@ -123,10 +123,6 @@ module.exports =
     (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
     THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     """
-  'tweetnacl@0.14.3':
-    repository: 'https://github.com/dchest/tweetnacl-js'
-    license: 'Public Domain'
-    source: 'https://github.com/dchest/tweetnacl-js/blob/1042c9c65dc8f1dcb9e981d962d7dbbcf58f1fdc/COPYING.txt says public domain.'
   'json-schema@0.2.2':
     repository: 'https://github.com/kriszyp/json-schema'
     license: 'BSD'