Revert to Laravel 5.* until code changes to support Laravel 6.

Author: danielme85

composer.json

@@ -12,11 +12,12 @@
     ],
     "require": {
         "php": ">=7.1",
-        "illuminate/support": ">=5.6"
+        "illuminate/support": "~5.6"
     },
     "require-dev": {
-        "orchestra/testbench": "~4.0",
-        "jenssegers/mongodb": ">=3.4"
+        "orchestra/testbench": ">=3.7",
+        "jenssegers/mongodb": ">=3.4",
+        "mockery/mockery": "^1.0"
     },
     "autoload": {
         "psr-4": {