Support safe ^2.0

Author: dbrekelmans

composer.json

@@ -12,10 +12,10 @@
     "require": {
         "php": "^7.1 || ^8.0",
         "phpstan/phpstan": "^1.0",
-        "thecodingmachine/safe": "^1.0"
+        "thecodingmachine/safe": "^1.0 || ^2.0"
     },
     "require-dev": {
-        "phpunit/phpunit": "^7.5.2",
+        "phpunit/phpunit": "^7.5.2 || ^8.0",
         "php-coveralls/php-coveralls": "^2.1",
         "squizlabs/php_codesniffer": "^3.4"
     },