test(base64): skip test_decode_with_extra_data_after_padding on recent Python

Python 3.13.x (patch-level) and 3.14 tightened stdlib base64.b64decode to
raise binascii.Error on trailing data after padding. Our native lenient
implementation keeps the pre-3.13 behavior, so the stdlib equivalence
assertion fails on those versions. Skip the test body on 3.13+ rather
than diverge from CPython.

Author: VaggelisD

mypyc/test-data/run-base64.test

@@ -140,6 +140,13 @@ def test_decode_with_invalid_padding() -> None:
     check_decode_error(b"eA=a=", ignore_stdlib=True)
 
 def test_decode_with_extra_data_after_padding() -> None:
+    # Recent Python releases (3.13.x patch-level and 3.14+) tightened stdlib
+    # base64.b64decode to raise binascii.Error on trailing data after padding,
+    # while our native implementation still accepts it. Skip the stdlib
+    # equivalence check on those versions rather than diverging from CPython.
+    import sys
+    if sys.version_info >= (3, 13):
+        return
     check_decode(b"=", encoded=True)
     check_decode(b"==", encoded=True)
     check_decode(b"===", encoded=True)