update travis config

.travis.yml

@@ -9,7 +9,7 @@ env:
     - ES_VERSION=7.4.0 ES_DOWNLOAD_URL=https://artifacts.elastic.co/downloads/elasticsearch/elasticsearch-${ES_VERSION}-linux-x86_64.tar.gz
 install:
   - wget ${ES_DOWNLOAD_URL}
-  - tar -xzf elasticsearch-${ES_VERSION}.tar.gz
+  - tar -xzf elasticsearch-${ES_VERSION}-linux-x86_64.tar.gz
   - ./elasticsearch-${ES_VERSION}/bin/elasticsearch -d
 before_script:
   - if [ "$GITHUB_COMPOSER_AUTH" ]; then composer config -g github-oauth.github.com $GITHUB_COMPOSER_AUTH; fi