Update minimum Laravel version

Author: driesvints

composer.json

@@ -13,9 +13,9 @@
         "php": ">=7.1.3",
         "ext-dom": "*",
         "ext-json": "*",
-        "illuminate/database": "^5.7",
-        "illuminate/http": "^5.7",
-        "illuminate/support": "^5.6",
+        "illuminate/database": "~5.7.0",
+        "illuminate/http": "~5.7.0",
+        "illuminate/support": "~5.7.0",
         "mockery/mockery": "^1.0",
         "phpunit/phpunit": "^7.0|^8.0",
         "symfony/console": "^4.2",