Changes of color palettes

[sainnhe]

Any changes to the definition of colors in gruvbox-material/autoload/gruvbox_material.vim and gruvbox-material-vscode/src/palette will be noted here.

[sainnhe]

In commit b7d04a4

• bg_red: #f2594b -> #db4740

[sainnhe]

In commit f87bb7a

• bg_statusline3: #665c54 -> #5b534d

[sainnhe]

In commit b0f0d36

• bg_visual_yellow is added.
• bg_visual_green, bg_visual_blue and bg_visual_red in soft dark variant are changed.

[sainnhe]

In commit ba133b3

• The diff and visual background colors is adjusted in the light variant.