Merge pull request #2 from biurad/renovate/pin-dependencies

Pin dependency phpunit/phpunit to 7.5.20

Author: divineniiquaye

composer.json

@@ -31,7 +31,7 @@
         "psr/simple-cache": "^1.0"
     },
     "require-dev": {
-        "phpunit/phpunit": "~7.0",
+        "phpunit/phpunit": "7.5.20",
         "cache/integration-tests": "dev-master"
     },
     "autoload": {