Simplify pytest configuration

It seems to be doing fine on its own.

As a bonus this restores running doctests from the injector source code
which I broke when I made it a package (code in injector/__init__.py)
instead of a simple module. *But* we need to start skipping running
doctests for get_bindings on Python versions that don't support
Annotated (or don't support it well enough).

conftest.py

@@ -1,7 +0,0 @@
-import os.path
-
-test_sources = ['injector', 'injector_test.py', 'README.md']
-
-
-def pytest_ignore_collect(path, config):
-    return not os.path.basename(str(path)) in test_sources

injector/__init__.py

@@ -1003,6 +1003,10 @@ def get_bindings(callable: Callable) -> Dict[str, type]:
         >>> get_bindings(function3)
         {'a': <class 'int'>}
 
+        >>> import sys, pytest
+        >>> if sys.version_info < (3, 7, 0):
+        ...     pytest.skip('Python 3.7.0 required for sufficient Annotated support')
+
         >>> # The simple case of no @inject but injection requested with Inject[...]
         >>> def function4(a: Inject[int], b: str) -> None:
         ...     pass

pytest.ini

@@ -1,4 +1,3 @@
 [pytest]
-python_files = injector_test.py injector_test_py3.py
 addopts = -v --tb=native --doctest-glob=*.md --doctest-modules --cov-report term --cov-report html --cov-report xml --cov=injector --cov-branch
 norecursedirs = __pycache__ *venv* .git build

setup.cfg

@@ -1,5 +1,2 @@
-[pytest]
-addopts = -rsxX -q --doctest-modules --doctest-glob=README.md injector injector_test.py README.md
-
 [wheel]
 universal = True