Move old C API tests for floats to Lib/test/test_capi/

[skirpichev]

After #111624, we have C API tests for PyFloat_* both in Lib/test/test_float.py (pack/unpack tests) and Lib/test/test_capi/test_float.py. I think we should move remaining tests to Lib/test/test_capi/.

Linked PRs

• gh-111765: move old PyFloat_* tests to Lib/test/test_capi/test_float.py  #111766
• [3.12] gh-111765: Move old PyFloat_* tests to Lib/test/test_capi/test_float.py (GH-111766) #111818

[skirpichev]

@serhiy-storchaka, I think this could be closed. The test_float.py still imports _testcapi:

cpython/Lib/test/test_float.py

Lines 663 to 668 in a077b2f

	@support.requires_IEEE_754
	@unittest.skipIf(_testcapi is None, 'needs _testcapi')
	def test_serialized_float_rounding(self):
	FLT_MAX = _testcapi.FLT_MAX
	self.assertEqual(struct.pack("<f", 3.40282356e38), struct.pack("<f", FLT_MAX))
	self.assertEqual(struct.pack("<f", -3.40282356e38), struct.pack("<f", -FLT_MAX))

but this is rather a bug in sys.float_info.