tag: update release tag number

Author: rafael_chicoli

.travis.yml

@@ -60,9 +60,9 @@ matrix:
       if: type IN (pull_request)
 
     - stage: release
-      env: MAJOR_RELEASE=true
+      # env: MAJOR_RELEASE=true
       # it would be nice to map github labels instead
-      # env: RELEASE_TAG=0.3.0
+      env: RELEASE_TAG=0.4.0
       if: type IN (push)
       script:
         - ./scripts/git-release.sh
@@ -80,4 +80,4 @@ after_install:
 # addons:
 #   apt:
 #     packages:
-#       - docker-ce=17.05.0~ce-0~ubuntu-trusty
+#       - docker-ce=17.05.0~ce-0~ubuntu-trusty