ci: Fix installation of python packages in deploy-* jobs
ci: Fix installation of python packages in deploy-* jobs

This commit fixes a regression introduced in 529dccd5 (circleci: Use
workflow to separately upload latest and tagged releases). It creates
a virtual environment to avoid error like the following:

  Could not install packages due to an EnvironmentError: [Errno 13] Permission denied: '/usr/local/lib/python3.7/site-packages/lxml'

QIICR/dcmqi,QIICR/dcmqi,QIICR/dcmqi,QIICR/dcmqi,QIICR/dcmqi