build: fix testing comopser script

Signed-off-by: Bart Jaskulski <bartek.jaskulski@wpdesk.net>

composer.json

@@ -34,7 +34,7 @@
 	"scripts": {
 		"test:phpstan": "./tools/phpstan --configuration=phpstan.neon.dist --memory-limit=-1 analyze",
 		"test:phpcs": "./tools/phpcs",
-		"test:phpunit": "./tools/phpunit --bootstrat=tests/bootstrap.php",
+		"test:phpunit": "./tools/phpunit --bootstrap tests/bootstrap.php tests",
 		"test": [
 			"@test:phpcs",
 			"@test:phpstan",