chore(website): remove deprecated Sass resources

[wellwelwel]

This PR just remove the noise warnings when working in the website due to deprecated Sass resources.

Related:

• Deprecate and remove @import sass/sass#3513.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 88.45%. Comparing base (78b1662) to head (1da545c).
Report is 1 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #3346   +/-   ##
=======================================
  Coverage   88.45%   88.45%           
=======================================
  Files          83       83           
  Lines       13067    13067           
  Branches     1392     1393    +1     
=======================================
  Hits        11558    11558           
  Misses       1509     1509           

Flag	Coverage Δ
compression-0	88.45% <ø> (ø)
compression-1	88.45% <ø> (ø)
tls-0	87.84% <ø> (ø)
tls-1	88.21% <ø> (ø)

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