Bump postcss from 7.0.27 to 7.0.39 in /gui

Bumps [postcss](https://github.com/postcss/postcss) from 7.0.27 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](https://github.com/postcss/postcss/compare/7.0.27...7.0.39)

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

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

gui/package-lock.json

@@ -11454,6 +11454,12 @@
       "integrity": "sha1-Ywn04OX6kT7BxpMHrjZLSzd8nns=",
       "dev": true
     },
+    "picocolors": {
+      "version": "0.2.1",
+      "resolved": "https://registry.npmjs.org/picocolors/-/picocolors-0.2.1.tgz",
+      "integrity": "sha512-cMlDqaLEqfSaW8Z7N5Jw+lyIW869EzT73/F5lhtY9cLGoVxSXznfgfXMO0Z5K0o0Q2TkTXq+0KFsdnSe3jDViA==",
+      "dev": true
+    },
     "pify": {
       "version": "4.0.1",
       "resolved": "https://registry.npm.taobao.org/pify/download/pify-4.0.1.tgz?cache=0&sync_timestamp=1581725110840&other_urls=https%3A%2F%2Fregistry.npm.taobao.org%2Fpify%2Fdownload%2Fpify-4.0.1.tgz",
@@ -11586,30 +11592,20 @@
       "dev": true
     },
     "postcss": {
-      "version": "7.0.27",
-      "resolved": "https://registry.npm.taobao.org/postcss/download/postcss-7.0.27.tgz?cache=0&sync_timestamp=1582022111849&other_urls=https%3A%2F%2Fregistry.npm.taobao.org%2Fpostcss%2Fdownload%2Fpostcss-7.0.27.tgz",
-      "integrity": "sha1-zGfNxrDao3UQW3xCSoVWc0X8VNk=",
+      "version": "7.0.39",
+      "resolved": "https://registry.npmjs.org/postcss/-/postcss-7.0.39.tgz",
+      "integrity": "sha512-yioayjNbHn6z1/Bywyb2Y4s3yvDAeXGOyxqD+LnVOinq6Mdmd++SW2wUNVzavyyHxd6+DxzWGIuosg6P1Rj8uA==",
       "dev": true,
       "requires": {
-        "chalk": "^2.4.2",
-        "source-map": "^0.6.1",
-        "supports-color": "^6.1.0"
+        "picocolors": "^0.2.1",
+        "source-map": "^0.6.1"
       },
       "dependencies": {
         "source-map": {
           "version": "0.6.1",
-          "resolved": "https://registry.npm.taobao.org/source-map/download/source-map-0.6.1.tgz",
-          "integrity": "sha1-dHIq8y6WFOnCh6jQu95IteLxomM=",
+          "resolved": "https://registry.npmjs.org/source-map/-/source-map-0.6.1.tgz",
+          "integrity": "sha512-UjgapumWlbMhkBgzT7Ykc5YXUT46F0iKu8SGXq0bcwP5dz/h0Plj6enJqjz1Zbq2l5WaqYnrVbwWOWMyF3F47g==",
           "dev": true
-        },
-        "supports-color": {
-          "version": "6.1.0",
-          "resolved": "https://registry.npm.taobao.org/supports-color/download/supports-color-6.1.0.tgz?cache=0&sync_timestamp=1573220230429&other_urls=https%3A%2F%2Fregistry.npm.taobao.org%2Fsupports-color%2Fdownload%2Fsupports-color-6.1.0.tgz",
-          "integrity": "sha1-B2Srxpxj1ayELdSGfo0CXogN+PM=",
-          "dev": true,
-          "requires": {
-            "has-flag": "^3.0.0"
-          }
         }
       }
     },