Fix uv sync / uv venv with pytest

uv sync
source .venv/bin/activate
cd test
python -m pytest .

- Update default bundled capnproto to 1.4.0
- Cleanup pyproject.toml
- Remove Pipfile and requirements.txt

buildutils/bundle.py

@@ -25,7 +25,7 @@ pjoin = os.path.join
 #
 
 
-bundled_version = (1, 0, 1)
+bundled_version = (1, 4, 0)
 libcapnp_name = "capnproto-c++-%i.%i.%i.tar.gz" % (bundled_version)
 libcapnp_url = "https://capnproto.org/" + libcapnp_name