Update Elasticsearch php to version 6.1 (#183)

* Update Elasticsearch php to version 6.1
* Tests with PHP 7.3

Author: romulowspp

.travis.yml

@@ -1,11 +1,11 @@
 language: php
 
 php:
-    - 5.5
-    - 5.6
+    - 7.1
+    - 7.3
 
 include:
-    - php: 5.5
+    - php: 7.1
       env: dependencies=lowest
 
 before_script:

composer.json

@@ -21,7 +21,7 @@
     "illuminate/database": "~4.2|^5",
     "illuminate/config": "~4.2|^5",
     "nesbot/carbon": "~1.0",
-    "elasticsearch/elasticsearch": "~6.0"
+    "elasticsearch/elasticsearch": "~6.1"
   },
   "require-dev": {
     "phpunit/phpunit": "~4.2|~5.0",