Fails with `ValueError: invalid literal` for httpx `1.0.dev*`

[janbrasna]

Since the upper constraint was removed in #67 and httpx started publishing pre-release 1.x versions like 1.0.dev2 there seem to be expectations not compatible with this:

    from sanic_testing.testing import SanicTestClient
  File "/home/runner/.tox/py311-s23/lib/python3.11/site-packages/sanic_testing/__init__.py", line 1, in <module>
    from sanic_testing.manager import TestManager
  File "/home/runner/.tox/py311-s23/lib/python3.11/site-packages/sanic_testing/manager.py", line 3, in <module>
    from sanic_testing.testing import SanicASGITestClient, SanicTestClient
  File "/home/runner/.tox/py311-s23/lib/python3.11/site-packages/sanic_testing/testing.py", line 25, in <module>
    httpx_version = tuple(
                    ^^^^^^
ValueError: invalid literal for int() with base 10: 'dev2'

that points here:

sanic-testing/sanic_testing/testing.py

Lines 25 to 27 in 66b72d2

	httpx_version = tuple(
	map(int, httpx.__version__.strip(ascii_lowercase).split("."))
	)

Not sure if there are any actual API breaking changes relevant, but it seems surprising pre-release dependencies are resolved in the first place(?)