CompatHelper: bump compat for "Colors" to "0.11"

[github-actions]

This pull request changes the compat entry for the Colors package from 0.9 to 0.9, 0.11.

This keeps the compat entries for earlier versions.

Note: I have not tested your package with this new compat entry. It is your responsibility to make sure that your package tests pass before you merge this pull request.

[kimikage]

A workaround for the segfaults was added to FixedPointNumbers.jl (v0.7.1).
For now, segfaults have not occurred in the CI tests.
https://travis-ci.org/kimikage/Gadfly.jl/builds/633820527

Note that we did not add the workaround to ColorTypes.jl, which used to need the workaround before (cf. #1369 (comment)). The difference is that the workaround has been added to FileIO.jl and Colors.jl, and some packages have been updated.
Since we have not fully clarified the cause of the bug, we cannot say whether we have successfully suppressed the segfault or just reduced the probability of its occurrence.

IMO, since it will take some time to complete the resolution, and this is considered to be a problem only on Julia v1.0.x, I think it is OK to release new version with [compat] entry Colors = "0.9, 0.11".

[bjarthur]

what about Colors v0.10? sorry, but i haven't really made the effort to what's going on over there.

[kimikage]

I think Colors v0.10.2 is potentially compatible. However, since Compose.jl does not support v0.10 for now, I have not executed enough CI tests.