Remove phpcov

Remove phpcov, it's not compatible and suggested to be installed with phar instead of composer, see sebastianbergmann/phpcov#96

Author: softdevee

composer.json

@@ -29,8 +29,7 @@
         "phpunit/phpunit": "^8.4|^9.0",
         "orchestra/testbench": "^5.0",
         "mockery/mockery": "^1.3.1",
-        "doctrine/dbal": "^2.6",
-        "phpunit/phpcov": "^6.0|^7.0"
+        "doctrine/dbal": "^2.6"
     },
     "autoload": {
         "psr-0": {