Change all ramp colors to orange

[logical-1985516]

Fixes reposense#2216

Explanation

The color in a ramp indicates the day in which a commit is done, in a 5-day cycle. As quoted from issue reposense#2216,

To a viewer, this may to confusing. For example, the viewer might think the color of the ramp indicates the file types that were modified in that commit.

The color in the ramp is currently used to indicate the day the commit was done, so that it is easy to see which commits were done on a specific day, across repos. Personally, I don't think this feature adds much value.

So, one option is to use the same color for ramps so that it is clear the colors are used to indicate file type breakdown only.

This PR changes the colors in the ramp to only orange. The screenshot below shows the change.

Screenshot