Description of the problem

The orange and green colours at the "Scatter plots with a legend" gallery example can be hard to distinguish for people with red/green colour vision deficiencies. We should choose different colours instead if possible.

v0.3.0 original colour	Deuteranopia (no green) simulation

The line that needs to change is this:

References:

• https://developer.mozilla.org/en-US/docs/Tools/Accessibility_inspector/Simulation
• https://docs.generic-mapping-tools.org/6.1/gmtcolors.html#list-of-colors
• https://colorbrewer2.org/#type=qualitative&scheme=Set2&n=3