test new phpunit (#112)

* test new phpunit

* 10 available only from 8.1, keep it as it is for now

Author: stefanak-michal

composer.json

@@ -8,11 +8,11 @@
     "license": "MIT",
     "minimum-stability": "stable",
     "require": {
-        "php": ">=8",
+        "php": "^8",
         "ext-mbstring": "*"
     },
     "require-dev": {
-        "phpunit/phpunit": ">=9"
+        "phpunit/phpunit": "^9"
     },
     "support": {
         "issues": "https://github.com/neo4j-php/Bolt/issues",