Fixate more compatible PHPUnit version

Author: ondrejmirtes

.github/workflows/build.yml

@@ -120,8 +120,8 @@ jobs:
         run: "composer update --no-interaction --no-progress"
 
       - name: "Downgrade PHPUnit"
-        if: matrix.php-version == '7.2' || matrix.php-version == '7.3'
-        run: "composer require --dev phpunit/phpunit:^7.5.20 --update-with-dependencies"
+        if: matrix.php-version == '7.2'
+        run: "composer require --dev phpunit/phpunit:^8.5.31 --update-with-dependencies"
 
       - name: "Tests"
         run: "make tests"

composer.json

@@ -25,7 +25,7 @@
 		"php-parallel-lint/php-parallel-lint": "^1.2",
 		"phpstan/phpstan-phpunit": "^1.0",
 		"phpstan/phpstan-strict-rules": "^1.0",
-		"phpunit/phpunit": "^9.5"
+		"phpunit/phpunit": "~9.5.28"
 	},
 	"config": {
 		"platform": {