Test AESGCM stream: ignore failures for small auth tags

Smaller authentication tags may not be supported by the library.
This fix makes the test work for the default case that tags
should be minimum 12 bytes in size.

tests/test_aesgcmstream.py

@@ -25,7 +25,7 @@ from wolfcrypt._ffi import lib as _lib
 if _lib.AESGCM_STREAM_ENABLED:
     import pytest
     from wolfcrypt.utils import t2b
-    from wolfcrypt.exceptions import WolfCryptError
+    from wolfcrypt.exceptions import WolfCryptError, WolfCryptApiError
     from binascii import hexlify as b2h
     from wolfcrypt.ciphers import AesGcmStream
 
@@ -141,7 +141,14 @@ if _lib.AESGCM_STREAM_ENABLED:
         for good in (4, 8, 12, 13, 14, 15, 16):
             gcm = AesGcmStream(key, iv, tag_bytes=good)
             gcm.encrypt("hello world")
-            tag = gcm.final()
+            try:
+                tag = gcm.final()
+            except WolfCryptApiError as exception:
+                if "(-173)" in str(exception) and good < 12:
+                    # Probably this authentication tag size is not supported,
+                    # the minimum is 12 by default. Ignore.
+                    continue
+                raise
             assert len(tag) == good
 
     def test_decrypt_rejects_wrong_tag_length():