Support PHPUnit 9

Author: mbabker

composer.json

@@ -9,10 +9,13 @@
         "php": "^7.2.5"
     },
     "require-dev": {
-        "doctrine/inflector": "~1.2",
-        "joomla/coding-standards": "~2.0@alpha",
-        "joomla/test": "~1.0",
-        "phpunit/phpunit": "~8.2"
+        "doctrine/inflector": "^1.2",
+        "joomla/coding-standards": "^2.0@alpha",
+        "joomla/test": "^2.0",
+        "phpunit/phpunit": "^8.5|^9.0"
+    },
+    "conflict": {
+        "doctrine/inflector": "<1.2"
     },
     "suggest": {
         "ext-mbstring": "For improved processing",
@@ -45,6 +48,7 @@
             "Joomla\\String\\Tests\\": "Tests/"
         }
     },
+    "minimum-stability": "dev",
     "extra": {
         "branch-alias": {
 	        "dev-2.0-dev": "2.0-dev"