D3699: run-tests: follow-up on the test-case format

[Yuya Nishihara]

> > test-run-tests.t:1669
> > +  --- $TESTTMP/anothertests/cases/test-cases-advanced-cases.t
> > +  +++ $TESTTMP/anothertests/cases/test-cases-advanced-cases.t.casewith!@#$%^&*()chars.err
> > +  @@ -1,3 +1,3 @@
> 
> Windows can't create the test directory with all of the reserved characters here.  Are these necessary?

Maybe no? I think alphanumerics + '-' should be enough, and allowing shell
meta characters is potentially unsafe.