The usual way is to put conflicting versions in optional-dependencies, and then build one target for each conflicting set of deps. That'd work fine if the code

The usual way is to put conflicting versions in optional-dependencies, and then build one target for each conflicting set of deps. That'd work fine if the code path of one target doesn't touch the others, which is often the case. You'd obviously need to have tests for both targets, possibly using a flexible test runner like `nox` to setup separate test env for each target.