Update devDependencies

[XhmikosR]

• @popperjs/core ^2.11.4 → ^2.11.5
• clean-css-cli ^5.5.2 → ^5.6.0
• karma-rollup-preprocessor ^7.0.8 → ^7.0.7
• stylelint 14.2.0 → 14.6.1

[julien-deramond]

@XhmikosR Got a group of questions regarding the "currentColor" → "currentcolor" modification:

• I don't know if you're aware of that but there is a remaining currentColor in

  bootstrap/scss/_spinners.scss

  Line 32 in 87da340

  border: var(--#{$prefix}spinner-border-width) solid currentColor;

  not detected automatically.
• There are remaining currentColor in some Markdown files (migration.md, placeholders.md, spinners.md). I suppose it is normal that they are not automatically detected, but is a modification needed here?
• There are remaining currentColor in the SVGs (inline in Markdown files or in .svg files). Is a modification needed in your opinion?

[XhmikosR]

@julien-deramond sorry for the late reply:

1. I guess it's an issue in stylelint or stylelint-scss so it should be reported there
2. we could change those instances too later for consistency assuming the first point is also fixed
3. not sure about SVGs, it might be OK nowadays to use the lowercase attribute but I wouldn't bother with them at this point