Potential fix for code scanning alert no. 1: Workflow does not contain permissions

Co-authored-by: Copilot Autofix powered by AI <62310815+github-advanced-security[bot]@users.noreply.github.com>

Author: serhiidonii

.github/workflows/unit_tests.yaml

@@ -1,5 +1,8 @@
 name: Unit tests
 
+permissions:
+  contents: read
+
 on:
   pull_request:
     branches: [ main, develop ]