community/py3-asn1-modules: fix tests

Fix failed tests due to import of removed pyasn1.compat.octets, leading to a rebuild error on a 3.21 builder.

ImportError while importing test module '/home/buildozer/aports/community/py3-asn1-modules/src/pyasn1_modules-0.4.1/tests/test_pem.py'.
Hint: make sure your test modules/packages have valid Python names.
Traceback:
/usr/lib/python3.12/importlib/__init__.py:90: in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
tests/test_pem.py:10: in <module>
    from pyasn1.compat.octets import ints2octs
E   ModuleNotFoundError: No module named 'pyasn1.compat.octets'

Tests affected:

ERROR tests/test_pem.py
ERROR tests/test_rfc3770.py
ERROR tests/test_rfc4073.py
ERROR tests/test_rfc4334.py
ERROR tests/test_rfc5755.py
ERROR tests/test_rfc6032.py
ERROR tests/test_rfc6120.py