Remove explicit sets of PYPI_VENDOR_DIR and let integration conftest do its thing

.env

@@ -1,2 +1 @@
 HELLO=WORLD
-PYPI_VENDOR_DIR="./tests/pypi/"

run-tests.bat

@@ -4,4 +4,4 @@ virtualenv R:\.venv
 R:\.venv\Scripts\pip install -e . --upgrade --upgrade-strategy=only-if-needed
 R:\.venv\Scripts\pipenv install --dev
 
-SET RAM_DISK=R:&& SET PYPI_VENDOR_DIR=".\tests\pypi\" && R:\.venv\Scripts\pipenv run pytest -n auto -v tests --tap-stream > report.tap
+SET RAM_DISK=R: && R:\.venv\Scripts\pipenv run pytest -n auto -v tests --tap-stream > report.tap

run-tests.sh

@@ -4,9 +4,6 @@
 
 set -eo pipefail
 
-# Set the PYPI vendor URL for pytest-pypi.
-PYPI_VENDOR_DIR="$(pwd)/tests/pypi/"
-export PYPI_VENDOR_DIR
 export PYTHONIOENCODING="utf-8"
 export LANG=C.UTF-8