Use the base name of the generating script, not the full path

Otherwise the generation is sensitive to trivial differences such as
running `tests/scripts/generate_psa_tests.py` vs
`./tests/scripts/generate_psa_tests.py` vs an absolute path.

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>

scripts/mbedtls_dev/test_case.py

@@ -17,6 +17,7 @@
 # limitations under the License.
 
 import binascii
+import os
 import sys
 from typing import Any, Iterable, List, Optional
 import typing_extensions #pylint: disable=import-error
@@ -98,7 +99,7 @@ def write_data_file(filename: str,
     If the file already exists, it is overwritten.
     """
     if caller is None:
-        caller = sys.argv[0]
+        caller = os.path.basename(sys.argv[0])
     with open(filename, 'w') as out:
         out.write('# Automatically generated by {}. Do not edit!\n'
                   .format(caller))