Fix SASS deprecation warnings

[psurukuc]

Acknowledge the following

• I carefully read and followed the Getting Started guide.
• I read through FAQ and searched through the past issues, none of which addressed my issue.
• The issue I am raising is a potential bug in al-folio and not just a usage question.
  [For usage questions, please post in the Discussions instead of raising an issue.]

Describe the bug
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To Reproduce
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1. Go to '...'
2. Click on '....'
3. Scroll down to '....'
4. See error

Expected behavior
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Screenshots
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System (please complete the following information):

• OS: [e.g. iOS]
• Browser (and its version) [e.g. chrome, safari]
• Jekyll version [e.g. 3.8.7]
• Ruby version [e.g. 2.6.5]

Additional context
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