Mark test as 'run-always'

[MartinBernstorff]

Is your feature request related to a problem? Please describe.
I have a few tests which depend on .cfg files on disk. Since testmon doesn't support checking those .cfg files, a super simple solution is to run the test all the time.

Describe the solution you'd like
Run all tests with a specific pytest or testmon decorator.

Describe alternatives you've considered
None so far.