Update nette/tester requirement from 2.4.2 to 2.4.3

Updates the requirements on nette/tester to permit the latest version.

---
updated-dependencies:
- dependency-name: nette/tester
  dependency-type: direct:development
...

Signed-off-by: dependabot[bot] <support@github.com>

composer.json

@@ -21,7 +21,7 @@
         "nette/forms": "^3.1@dev"
     },
     "require-dev": {
-        "nette/tester": "2.4.2",
+        "nette/tester": "2.4.3",
         "mockery/mockery": "1.5.0",
         "phpstan/phpstan": "1.8.2",
         "phpstan/phpstan-strict-rules": "1.4.2",