Deprecated warnings for CSS

[stanleylhs]

When running the features test, we see the following warnings:

autoprefixer: ~/fat_free_crm/app/assets/stylesheets/application.css.erb:2056:3: Replace color-adjust to print-color-adjust. The color-adjust shorthand is currently deprecated.
autoprefixer: ~/fat_free_crm/app/assets/stylesheets/application.css.erb:11913:3: Gradient has outdated direction syntax. New syntax is like `to left` instead of `right`.
autoprefixer: ~/fat_free_crm/app/assets/stylesheets/bootstrap-custom.scss:2056:3: Replace color-adjust to print-color-adjust. The color-adjust shorthand is currently deprecated.
autoprefixer: ~/fat_free_crm/app/assets/stylesheets/common.scss:1058:3: Gradient has outdated direction syntax. New syntax is like `to left` instead of `right`.

These can be fixed by upgrading to Boostrap 5.3, but doing so break some UI elements, so we leave it as is for now.

On v5.3, rails server will fail to start as variable not found, add

@import "bootstrap/variables";
@import "bootstrap/maps";

at the top of bootstrap-custom.scss to fix it.