Update CI config: allow "nslookup check" failure

Author: PeterDaveHello

.travis.yml

@@ -3,14 +3,17 @@
 language: minimal
 dist: focal
 
+env:
+  global: DUMB_GLOBAL_ENV=TO_ENABLE_ALLOW_FAUILURE
+
 git:
   depth: 5
 
 stages:
   - test
 
 jobs:
-  include:
+  allow_failures:
     - stage: test
       env:
         - task="nslookup check"
@@ -21,6 +24,7 @@ jobs:
         - echo 'nameserver 168.95.1.1' | sudo tee -a  /etc/resolv.conf
       script:
         - ./tests/nslookup
+  include:
     - stage: test
       env:
         - task="duplicate check"