PHPStan fixes

Author: mstefan21

composer.json

@@ -19,13 +19,14 @@
     ],
     "require": {
         "php": "^8.0",
-        "league/oauth2-client": "^2.0",
+        "league/oauth2-client": "^2.8",
         "firebase/php-jwt": "^7.0"
     },
     "require-dev": {
         "phpunit/phpunit": "~9.6.4",
-        "mockery/mockery": "~1.5.0",
-        "squizlabs/php_codesniffer": "~3.7.0"
+        "mockery/mockery": "^1.6",
+        "squizlabs/php_codesniffer": "~3.7.0",
+        "phpstan/phpstan": "^1.12"
     },
     "autoload": {
         "psr-4": {
@@ -37,6 +38,11 @@
             "Stevenmaguire\\OAuth2\\Client\\Test\\": "test/src/"
         }
     },
+    "config": {
+        "platform": {
+            "php": "8.0.0"
+        }
+    },
     "extra": {
         "branch-alias": {
             "dev-master": "1.0.x-dev"