Dmslogo

Fixed
- Updated minimum Python version to 3.9

- Update tests to use Python 3.11 and run on GitHub Actions rather than Travis CI

- Require at least `matplotlib` version 3.8 and modify code to work with that version.

Fixed
- Bypass error associated with loading some font files on Mac OS X.

Fixed
- Problems with title placements introduced in 0.6.0.

Added
- `alpha` argument to `ValueToColorMap.scale_bar`

Added
- Added `colorschemes.ValueToColorMap`.
- Ability to add overlay color bars to `draw_logo` (`heatmap_overlays` arg).

Added
- Added `min_upperlim` and `max_lowerlim` to `AxLimSetter`.