Bump postcss from 7.0.18 to 7.0.39

Bumps [postcss](https://github.com/postcss/postcss) from 7.0.18 to 7.0.39.
- [Release notes](https://github.com/postcss/postcss/releases)
- [Changelog](https://github.com/postcss/postcss/blob/7.0.39/CHANGELOG.md)
- [Commits](postcss/postcss@7.0.18...7.0.39)

---
updated-dependencies:
- dependency-name: postcss
  dependency-type: indirect
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

yarn.lock

@@ -4814,6 +4814,11 @@ performance-now@^2.1.0:
   resolved "https://registry.yarnpkg.com/performance-now/-/performance-now-2.1.0.tgz#6309f4e0e5fa913ec1c69307ae364b4b377c9e7b"
   integrity sha1-Ywn04OX6kT7BxpMHrjZLSzd8nns=
 
+picocolors@^0.2.1:
+  version "0.2.1"
+  resolved "https://registry.yarnpkg.com/picocolors/-/picocolors-0.2.1.tgz#570670f793646851d1ba135996962abad587859f"
+  integrity sha512-cMlDqaLEqfSaW8Z7N5Jw+lyIW869EzT73/F5lhtY9cLGoVxSXznfgfXMO0Z5K0o0Q2TkTXq+0KFsdnSe3jDViA==
+
 pify@^2.0.0, pify@^2.3.0:
   version "2.3.0"
   resolved "https://registry.yarnpkg.com/pify/-/pify-2.3.0.tgz#ed141a6ac043a849ea588498e7dca8b15330e90c"
@@ -5500,13 +5505,12 @@ postcss-values-parser@^2.0.0, postcss-values-parser@^2.0.1:
     uniq "^1.0.1"
 
 postcss@^7.0.0, postcss@^7.0.1, postcss@^7.0.14, postcss@^7.0.17, postcss@^7.0.2, postcss@^7.0.5, postcss@^7.0.6:
-  version "7.0.18"
-  resolved "https://registry.yarnpkg.com/postcss/-/postcss-7.0.18.tgz#4b9cda95ae6c069c67a4d933029eddd4838ac233"
-  integrity sha512-/7g1QXXgegpF+9GJj4iN7ChGF40sYuGYJ8WZu8DZWnmhQ/G36hfdk3q9LBJmoK+lZ+yzZ5KYpOoxq7LF1BxE8g==
+  version "7.0.39"
+  resolved "https://registry.yarnpkg.com/postcss/-/postcss-7.0.39.tgz#9624375d965630e2e1f2c02a935c82a59cb48309"
+  integrity sha512-yioayjNbHn6z1/Bywyb2Y4s3yvDAeXGOyxqD+LnVOinq6Mdmd++SW2wUNVzavyyHxd6+DxzWGIuosg6P1Rj8uA==
   dependencies:
-    chalk "^2.4.2"
+    picocolors "^0.2.1"
     source-map "^0.6.1"
-    supports-color "^6.1.0"
 
 prepend-http@^1.0.0:
   version "1.0.4"