Currently, tox-poetry-installer logs when it submits a dependency to the
(possibly-parallel) executor for installation, but not when the
installation is finished; this commit adds a log message when the
installation actually starts (in contrast with when the job is queued)
and a log message when the installation completes, along with the wall
time it took.
Rationale: I've noticed in some cases when running under Python 3.10
packages take much longer to install -- this logging should help
pinpoint culprits.
Remove custom package compatibility checks
Add checks using poetry's built in package compatibility checking using markers
Update venv integration to use poetry's venv processing tools
Remove unused constants
