fix: test-requirements.txt to reduce vulnerabilities

The following vulnerabilities are fixed by pinning transitive dependencies:
- https://snyk.io/vuln/SNYK-PYTHON-BLACK-6256273

Author: snyk-bot

test-requirements.txt

@@ -2,7 +2,7 @@
 
 mock >= 5.1.0, < 6
 autoflake==2.3.0
-black==24.2.0
+black==24.3.0
 flake8 >= 7.0.0, < 8
 griffe >= 0.41.2, < 1
 isort==5.13.2