Fix of deprecation in bootstrap4 theme with sass 1.63.3

[kkozlik]

Fixing these two deprecation warnings:

Deprecation Warning: Using / for division outside of calc() is deprecated and will be removed in Dart Sass 2.0.0.

Recommendation: math.div($fs, $fs * 0 + calc(1 / $rfs-rem-value)) or calc($fs / ($fs * 0 + calc(1 / $rfs-rem-value)))

More info and automated migrator: https://sass-lang.com/d/slash-div

   ╷
85 │       $fs: $fs / ($fs * 0 + calc(1 / $rfs-rem-value));
   │            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
   ╵
    node_modules/@selectize/selectize/dist/lib/bootstrap4/vendor/_rfs.scss 85:12      rfs()
    node_modules/@selectize/selectize/dist/lib/bootstrap4/vendor/_rfs.scss 199:3      font-size()
    node_modules/@selectize/selectize/dist/lib/bootstrap4/mixins/_buttons.scss 106:3  button-size()
    src/scss/custom.scss 48:5                                                         @import
    src/scss/gui.scss 116:9                                                           root stylesheet

Deprecation Warning: Using / for division outside of calc() is deprecated and will be removed in Dart Sass 2.0.0.

Recommendation: math.div($fs, $rfs-rem-value) or calc($fs / $rfs-rem-value)

More info and automated migrator: https://sass-lang.com/d/slash-div

   ╷
90 │       $rfs-static: #{$fs / $rfs-rem-value}rem#{$rfs-suffix};
   │                      ^^^^^^^^^^^^^^^^^^^^
   ╵
    node_modules/@selectize/selectize/dist/lib/bootstrap4/vendor/_rfs.scss 90:22      rfs()
    node_modules/@selectize/selectize/dist/lib/bootstrap4/vendor/_rfs.scss 199:3      font-size()
    node_modules/@selectize/selectize/dist/lib/bootstrap4/mixins/_buttons.scss 106:3  button-size()
    src/scss/custom.scss 48:5                                                         @import
    src/scss/gui.scss 116:9                                                           root stylesheet

[github-actions]

This pull request is stale because it has been open 90 days with no activity. Remove stale label or comment or this will be closed in 5 days

[kkozlik]

bump

[github-actions]

This pull request is stale because it has been open 90 days with no activity. Remove stale label or comment or this will be closed in 5 days

[kkozlik]

PR still needs to be accepted