Merge pull request #16 from simonellensohn/master

Fix "joiningTable" signature for 5.7

Author: calebporzio

composer.json

@@ -12,7 +12,7 @@
         "illuminate/database": "~5.6.0|~5.7.0"
     },
     "require-dev": {
-        "orchestra/testbench": "3.6.*",
+        "orchestra/testbench": "3.7.*",
         "phpunit/phpunit": "^7.0"
     },
     "autoload": {