Issue title: pytest tests/x86_64/test_load.py is failing
 Issue body: % `pytest tests/x86_64/test_load.py`
```
================================== test session starts ==================================
platform darwin -- Python 3.10.6, pytest-7.1.3, pluggy-1.0.0
rootdir: /Users/cclauss/Python/itinerant_futurizer/PeachPy
collected 1 item

tests/x86_64/test_load.py F                                                       [100%]

======================================= FAILURES ========================================
____________________________________ LoadAsm.runTest ____________________________________

self = <tests.x86_64.test_load.LoadAsm testMethod=runTest>

    def runTest(self):

        x = Argument(int32_t)
        y = Argument(float_)

        with Function("Multiply", (x, y), double_) as asm_multiply:
            reg_x = GeneralPurposeRegister32()
            LOAD.ARGUMENT(reg_x, x)

            xmm_y = XMMRegister()
            LOAD.ARGUMENT(xmm_y, y)

            xmm_x = XMMRegister()
            CVTSI2SD(xmm_x, reg_x)
            CVTSS2SD(xmm_y, xmm_y)

            MULSD(xmm_x, xmm_y)

            RETURN(xmm_x)

>       py_multiply = asm_multiply.finalize(abi.detect()).encode().load()

tests/x86_64/test_load.py:28:
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

self = <peachpy.x86_64.function.Function object at 0x103d3ef20>, abi = None

    def finalize(self, abi):
        from peachpy.x86_64.abi import ABI
        if not isinstance(abi, ABI):
>           raise TypeError("%s is not an ABI object" % str(abi))
E           TypeError: None is not an ABI object

peachpy/x86_64/function.py:308: TypeError
================================ short test summary info ================================
FAILED tests/x86_64/test_load.py38d1:d2b4:3d06:83e8:96a5:8c2:893d:aba5LoadAsm38d1:d2b4:3d06:83e8:96a5:8c2:893d:aba5runTest - TypeError: None is not an ABI object
=================================== 1 failed in 0.07s ===================================
```
 Comments: 
 Comment 0: This is supposed to work. Worth to dig into why `abi.detect()` fails.
 Comment 1: I will investigate but my bet going it is that the problem was discussed in PEP8 which was written 20+ years ago.
 Comment 2: I could not see it but I updated #130 to strict xfail the test if `abi.detect()` returned `None`.
{'source': 'GithubIssues', 'repo_name_with_owner': 'Maratyszcza/PeachPy', 'issue_id': 1381906717, 'repo_stars': 1820.0}