Don't allow latest-branca test failure

Author: Conengmo

.travis.yml

@@ -31,8 +31,6 @@ matrix:
   - name: "tarball"
     env: PY=3.7
   allow_failures:
-  - name: latest-branca
-    env: PY=3.7
   - name: linkcheck
     env: PY=3.7
   - name: notebooks-conding-standard