Update nette/tester requirement from v2.6.0 to v2.6.1

Updates the requirements on [nette/tester](https://github.com/nette/tester) to permit the latest version.
- [Release notes](https://github.com/nette/tester/releases)
- [Commits](nette/tester@v2.6.0...v2.6.1)

---
updated-dependencies:
- dependency-name: nette/tester
  dependency-version: 2.6.1
  dependency-type: direct:development
...

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

Author: dependabot[bot]

composer.json

@@ -21,7 +21,7 @@
         "nette/utils": "^3.2@dev || ^4.0@dev"
     },
     "require-dev": {
-        "nette/tester": "v2.6.0",
+        "nette/tester": "v2.6.1",
         "phpstan/phpstan": "2.2.1",
         "phpstan/phpstan-strict-rules": "2.0.11",
         "phpstan/phpstan-nette": "2.0.9",