fix(tests): description standardization

tests/test_email.py

@@ -2,7 +2,7 @@
 
 """
 Criticality: High
-Check that emails can be sent.
+Checks that emails can be sent.
 """
 
 from pathlib import Path

tests/test_fail2ban.py

 #!/usr/bin/env python3
 """
 Criticality: Low
-This test check the current state of the fail2ban service.
+Checks the current state of the fail2ban service.
 """
 
 from pathlib import Path

tests/test_postgresql.py

 #!/usr/bin/env python3
 """
 Criticality: High
-This test check the current state of the PostgreSQL database cluster.
+Checks the current state of the PostgreSQL database cluster.
 """
 
 from pathlib import Path