test_update_locks: Replace requests with jdcal
test_update_locks: Replace requests with jdcal

Using requests in tests fails when pipenv is de-vendored.
In this test, using any package with multiple versions
in the local pypi data will suffice to show the functionality
does work, but not with requests, or any devendored package.

Continuation of https://github.com/pypa/pipenv/issues/3644

kennethreitz/pipenv