Bump less from 2.7.3 to 3.9.0

[dependabot-preview]

Bumps less from 2.7.3 to 3.9.0.

Changelog

Sourced from less's changelog.

3.9.0

2018-11-28

• Added range([start=1], end, [step=1]) function to generate lists
• Fixes #3325 #3313 #3328

3.8.1

2018-08-07

• Fixes for sourcemaps and color functions
• Support for #RRGGBBAA color format
• Allows conversion of colors to rgba() or hsla()
• Pass-through output of unknown properties in color functions (allows var(--color) for example)

3.8.0

2018-07-22

• New feature: added rewrite urls to replace relative url option. Adds "local" option for modules

3.7.1

2018-07-11

• Fixes mistake in lessc (using console.warning instead of actual console.warn)
• Adds lessc tests

3.7.0

2018-07-11

• New each() function! See docs
• New math modes! Also see docs.
• Bug fixes

3.6.0

2018-07-10

• Allows plain conditions in if(true, 1, 2) (vs. if((true), 1, 2))
• Fixes svg-gradient() for Firefox
• Adds more 3rd-party tests for fewer surprises when upgrading
• Removes (broken) less-rhino implementation - use other Java ports

3.5.3

2018-07-06

• Reverts [**media**](https://github.com/media) eval change
• Other bug fixes

3.5.0

2018-07-05

• Feature: Namespaced Values / Maps e.g. color: [**color**](https://github.com/color)[primary]

... (truncated)

Commits

• 2001694 Release v3.9.0
• d787592 Adds range() function for lists (#3334)
• c816d82 Fixes #3325 #3313 #3328 - each() function fixes (#3333)
• 96fa179 Prevent Browserify from bundling Buffer (#3335)
• a84358d Update CHANGELOG.md
• 5230486 v3.8.1 (#3302)
• 33a3830 Fixes: #3300 (#3301)
• 4e903e8 Demonstrate 3.7 fixes #3160 (#3292)
• a9c69a3 Color function updates - #RRGGBBAA and CSS Variables (#3291)
• 59e919b v3.8.0 (#3293)
• Additional commits viewable in compare view

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[dependabot-preview]

Superseded by #407.