Update NPM dependencies to latest, and fix them (OSOE-671)

[Piedone]

Update all the NPM dependencies of the package to the latest versions, and make sure that the version numbers are not open but fixed to a specific version to avoid issues like Lombiq/Orchard-Base-Theme#84.

Note that updating sass to v1.65.1 causes this issue: Lombiq/Orchard-Base-Theme#84. If Bootstrap has a fix (twbs/bootstrap#39028) and we can update it in Base Theme, then do that; otherwise, keep sass on the latest still compatible version.

Jira issue

[wAsnk]

Updating stylelint to 15.10.3 from 14.14.0 would mean a major update that contains the following (breaking) changes:
https://stylelint.io/migration-guide/to-15

To sum up, they deprecated 76 rules because they are mostly styling related rules that can be achieved by pretty printers like Prettier so they won't support it anymore from the next major update.

Edit
These are the rules that we are using and deprecated:

'declaration-block-semicolon-newline-before': 'never-multi-line',
'function-comma-newline-after': 'always-multi-line',
'indentation': 4,
'max-line-length': 150,
'selector-list-comma-space-after': 'always-single-line',
'selector-list-comma-newline-after': 'always-multi-line',
'value-list-comma-newline-before': 'never-multi-line'

What should be done in this case?

[Piedone]

Eh, thanks for looking into this. Let's update to the latest 14.x for now then, and later we can look into upgrading to 15.x and see whether we should use Prettier or something.

[wAsnk]

Alright, then the stylelint-config-standard-scss package max version can be 6.1.0, because the next version (7.0.0) requires stylelint 15.x.