generate_psa_tests: fix docstring for tweak_key_pair_dependency function

Signed-off-by: Valerio Setti <valerio.setti@nordicsemi.no>
diff --git a/tests/scripts/generate_psa_tests.py b/tests/scripts/generate_psa_tests.py
index 851fe66..a77ece6 100755
--- a/tests/scripts/generate_psa_tests.py
+++ b/tests/scripts/generate_psa_tests.py
@@ -115,9 +115,11 @@
                for dep in dependencies):
         dependencies.append('DEPENDENCY_NOT_IMPLEMENTED_YET')
 
-# This helper function add the proper suffix to PSA_WANT_KEY_TYPE_xxx_KEY_PAIR
-# symbols according to the required usage.
 def tweak_key_pair_dependency(dep: str, usage: str):
+    """
+    This helper function add the proper suffix to PSA_WANT_KEY_TYPE_xxx_KEY_PAIR
+    symbols according to the required usage.
+    """
     ret_list = list()
     # Note: this LEGACY replacement for RSA is temporary and it's going to be
     # aligned with ECC one in #7772.