Fine tune configuration

.travis.yml

@@ -3,6 +3,7 @@ language: php
 php:
   - '7.1'
   - '7.2'
+  - '7.3'
   - nightly
 
 matrix:

composer.json

@@ -28,7 +28,7 @@
         "symfony/process": "^4.0",
         "webuni/commonmark-table-extension": "0.9.*",
         "webuni/front-matter": "^1.0.0"
-        
+
     },
     "suggest":{
         "ext-intl": "Allows to translate the modified at date"
@@ -43,6 +43,6 @@
     },
     "require-dev": {
         "phpunit/phpunit": "~7.4",
-        "mikey179/vfsStream": "^1.6"
+        "mikey179/vfsstream": "^1.6"
     }
 }