Pymmcore

Device interface version 71

Stub (.pyi) updates from tlambert03.
Update to dockerfile by ianhi.
Add `UnsignedVector` so that `getMultiROI()` can be called.
Drop Python 3.7 support.
Update MMCore to latest (bugfix only).

Device interface version 71

Note the device interface version has changed.

pymmcore no longer depends on Boost (only relevant if building from source).
MMCore 10.3.0, compared to 10.1.1 and earlier, uses higher resolution (depending on platform) timestamps in time delta measurements and logging. For time delta measurements monotonic timestamps are used, eliminating potential issues when the time zone changes.