Have been solving this issue for days, searched all the repos but not working.
The installation is keep geting all kinds of errors, including mmcv._ext, no torch blahblah.
In the end the solution is simple and stupid,
simply change this line mmdetection/mmdet/__init__.py 'mmcv_maximum_version = '2.5.0''
Then use mim to install whatever the latest mmcv, can already.