Update python virtual environment name

Change the repo python virtual environment name. This is a breaking
change. Repo synced after this commit need to rerun `m prereqs` or
`./scripts/install-prereqs -p scripts/python-requirements.txt -p
hw/opentitan-upstream/python-requirements.txt` or `mv cache/shodan-venv
cache/python-venv` to set up the python virtual environment.

Change-Id: Ice81a0e3f5ab8af3ddc991821765a25da0691964

setup.sh

diff --git a/setup.sh b/setup.sh
index 82ef87a..9fe56c0 100644
--- a/setup.sh
+++ b/setup.sh
@@ -64,7 +64,7 @@
 export RENODE_PORT=1234
 
 export PYTHONPATH="${PYTHONPATH}:${ROOTDIR}/cicd/"
-export PYTHON_SHODAN_ENV="${CACHE}/shodan-venv"
+export PYTHON_SHODAN_ENV="${CACHE}/python-venv"
 
 function renode
 {