gh-146453: fix _PyType_LookupByVersion for types with fixed pre-defined version tags

[kumaraditya303]

• Issue: _PyType_LookupByVersion returns NULL for types with static version tags #146453

Without the fix on current main branch, the added test fails:

./python -m test test_capi.test_opt -m test_cached_attributes_fixed_version_tag -v   
== CPython 3.15.0a7+ (heads/type-version-dirty:eeacb3eab0b, Mar 26 2026, 14:11:52) [Clang 21.1.8 (++20251221032922+2078da43e25a-1~exp1~2025
1221153059.70)]                                                                                                                            == Linux-6.6.87.2-microsoft-standard-WSL2-x86_64-with-glibc2.39 little-endian
== Python build: debug JIT
== cwd: /home/realkumaraditya/cpython/build/test_python_worker_37285æ
== CPU count: 12
== encodings: locale=UTF-8 FS=utf-8
== resources: all test resources are disabled, use -u option to unskip tests

Using random seed: 1734361391
0:00:00 load avg: 1.83 Run 1 test sequentially in a single process
0:00:00 load avg: 1.83 [1/1] test_capi.test_opt
test_cached_attributes_fixed_version_tag (test.test_capi.test_opt.TestUopsOptimization.test_cached_attributes_fixed_version_tag) ... FAIL

======================================================================
FAIL: test_cached_attributes_fixed_version_tag (test.test_capi.test_opt.TestUopsOptimization.test_cached_attributes_fixed_version_tag)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/home/realkumaraditya/cpython/Lib/test/test_capi/test_opt.py", line 3032, in test_cached_attributes_fixed_version_tag
    self.assertNotIn("_LOAD_ATTR_METHOD_NO_DICT", uops)
    ~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
AssertionError: '_LOAD_ATTR_METHOD_NO_DICT' unexpectedly found in ['_START_EXECUTOR', '_MAKE_WARM', '_SET_IP', '_CHECK_PERIODIC', '_CHECK_V
ALIDITY', '_ITER_CHECK_RANGE', '_GUARD_NOT_EXHAUSTED_RANGE', '_ITER_NEXT_RANGE', '_SET_IP', '_SWAP_FAST_3', '_SPILL_OR_RELOAD', '_POP_TOP', '_CHECK_VALIDITY', '_LOAD_FAST_BORROW_2', '_LOAD_FAST_BORROW_1', '_GUARD_TYPE_VERSION', '_LOAD_ATTR_METHOD_NO_DICT', '_SET_IP', '_SPILL_OR_RELOAD', '_CALL_METHOD_DESCRIPTOR_NOARGS', '_TIER2_RESUME_CHECK', '_CHECK_VALIDITY', '_GUARD_TOS_INT', '_GUARD_NOS_INT', '_BINARY_OP_ADD_INT', '_POP_TOP_INT', '_POP_TOP_NOP', '_SWAP_FAST_2', '_POP_TOP_INT', '_JUMP_TO_TOP', '_DEOPT', '_ERROR_POP_N', '_DEOPT', '_EXIT_TRACE', '_EXIT_TRACE', '_ERROR_POP_N', '_DEOPT', '_EXIT_TRACE', '_EXIT_TRACE', '_ERROR_POP_N', '_HANDLE_PENDING_AND_DEOPT', '_DEOPT', '_EXIT_TRACE', '_EXIT_TRACE']                                                                                                                              
----------------------------------------------------------------------
Ran 1 test in 0.006s

FAILED (failures=1)
test test_capi.test_opt failed
0:00:00 load avg: 1.83 [1/1/1] test_capi.test_opt failed (1 failure)

== Tests result: FAILURE ==

1 test failed:
    test_capi.test_opt

Total duration: 108 ms
Total tests: run=1 (filtered) failures=1
Total test files: run=1/1 (filtered) failed=1
Result: FAILURE

[Fidget-Spinner]

Oh wow, great find and fix, thanks!