Update dependency sass to v1.77.1

[renovate]

This PR contains the following updates:

Package	Change	Age	Adoption	Passing	Confidence
sass	1.75.0 -> 1.77.1

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Release Notes

sass/dart-sass (sass)

v1.77.1

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• Fix a crash that could come up with importers in certain contexts.

v1.77.0

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• Don't throw errors for at-rules in keyframe blocks.

v1.76.0

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• Throw errors for misplaced statements in keyframe blocks.

• Mixins and functions whose names begin with -- are now deprecated for
  forwards-compatibility with the in-progress CSS functions and mixins spec.
  This deprecation is named css-function-mixin.

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Configuration

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[coveralls]

coverage: 90.084%. remained the same
when pulling 14a69e1 on renovate/sass-1.x-lockfile
into 70d5b5b on master.