chore(deps): bump postcss-color-function from 4.0.1 to 4.1.0 (#1)

Bumps [postcss-color-function](https://github.com/postcss/postcss-color-function) from 4.0.1 to 4.1.0.
<details>
<summary>Changelog</summary>

*Sourced from [postcss-color-function's changelog](https://github.com/postcss/postcss-color-function/blob/master/CHANGELOG.md).*

> # 4.1.0 - 2019-04-01
> 
> - Added: `preserveCustomProps` option to preserve custom properties
> - Updated: `postcss` to 6.0.23 (patch)
> - Updated: `postcss-value-parser` to 3.3.1 (patch)
</details>
<details>
<summary>Commits</summary>

- See full diff in [compare view](https://github.com/postcss/postcss-color-function/commits)
</details>
<details>
<summary>Maintainer changes</summary>

This version was pushed to npm by [jonathantneal](https://www.npmjs.com/~jonathantneal), a new releaser for postcss-color-function since your current version.
</details>
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package.json

@@ -20,7 +20,7 @@
   },
   "dependencies": {
     "postcss-calc": "^7.0.1",
-    "postcss-color-function": "^4.0.1",
+    "postcss-color-function": "^4.1.0",
     "postcss-conditionals": "^2.1.0",
     "postcss-each": "^0.10.0",
     "postcss-easing-gradients": "^3.0.1",

yarn.lock

@@ -6558,15 +6558,15 @@ postcss-calc@^7.0.1:
     postcss-selector-parser "^5.0.0-rc.4"
     postcss-value-parser "^3.3.1"
 
-postcss-color-function@^4.0.1:
-  version "4.0.1"
-  resolved "https://registry.yarnpkg.com/postcss-color-function/-/postcss-color-function-4.0.1.tgz#402b3f2cebc3f6947e618fb6be3654fbecef6444"
-  integrity sha1-QCs/LOvD9pR+YY+2vjZU++zvZEQ=
+postcss-color-function@^4.1.0:
+  version "4.1.0"
+  resolved "https://registry.yarnpkg.com/postcss-color-function/-/postcss-color-function-4.1.0.tgz#b6f9355e07b12fcc5c34dab957834769b03d8f57"
+  integrity sha512-2/fuv6mP5Lt03XbRpVfMdGC8lRP1sykme+H1bR4ARyOmSMB8LPSjcL6EAI1iX6dqUF+jNEvKIVVXhan1w/oFDQ==
   dependencies:
     css-color-function "~1.3.3"
-    postcss "^6.0.1"
+    postcss "^6.0.23"
     postcss-message-helpers "^2.0.0"
-    postcss-value-parser "^3.3.0"
+    postcss-value-parser "^3.3.1"
 
 postcss-color-functional-notation@^2.0.1:
   version "2.0.1"
@@ -7112,7 +7112,7 @@ postcss@^5.0.0, postcss@^5.0.21, postcss@^5.0.4:
     source-map "^0.5.6"
     supports-color "^3.2.3"
 
-postcss@^6.0.0, postcss@^6.0.1, postcss@^6.0.14, postcss@^6.0.19, postcss@^6.0.6, postcss@^6.0.7, postcss@^6.0.9:
+postcss@^6.0.0, postcss@^6.0.1, postcss@^6.0.14, postcss@^6.0.19, postcss@^6.0.23, postcss@^6.0.6, postcss@^6.0.7, postcss@^6.0.9:
   version "6.0.23"
   resolved "https://registry.yarnpkg.com/postcss/-/postcss-6.0.23.tgz#61c82cc328ac60e677645f979054eb98bc0e3324"
   integrity sha512-soOk1h6J3VMTZtVeVpv15/Hpdl2cBLX3CAw4TAbkpTJiNPk9YP/zWcD1ND+xEtvyuuvKzbxliTOIyvkSeSJ6ag==