remove test code from the wheel

Adding MANIFEST.in only removed the test code from the sdist, but the
same files were also added to the wheel.

Using the exclude in pyproject.toml removes the test code from both the
sdist and the wheel, without having to use MANIFEST.in.

Author: arcctgx

MANIFEST.in

@@ -48,6 +48,7 @@ version = { attr = "arver.VERSION" }
 
 [tool.setuptools.packages.find]
 where = ["."]
+exclude = ["tests"]
 
 [tool.mypy]
 exclude = "build"