Upgrade sass-rails to version 5.0.6

[depfutester]

Hello,

We've upgraded a dependency and here is what you need to know:

gem name	version specification	new version
sass-rails	= 5.0.5	5.0.6

Please take a good look at the info here and the test results before merging this pull request.

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What changed?

Release Notes

From the Github release:

• Fixes deprecation warnings on Sprockets 3 (#382)

  Richard Schneeman

Commits

The new version differs by 11 commits:

• [ci skip] v5.0.6
• Merge pull request #382 from rails/schneems/fix-deprecations
• Sprockets 4 requires Ruby version >= 2.0.0
• "warning: `*' interpreted as argument prefix"
• `register_engine` would take a varargs
• Sprockets legacy processor interface
• Sprockets 2 render_engine has different arity
• Fix Sprockets 4 tests
• [close #381] Avoid Sprockets deprecations
• Merge pull request #383 from rails/schneems/fix-5-0-stable
• Fix tests with Rack and mime-types for Ruby 1.9

See the full diff.

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