build(deps): bump postcss from 7.0.35 to 7.0.39 in /frontend

Bumps [postcss](https://github.com/postcss/postcss) from 7.0.35 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/7.0.35...7.0.39)

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

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

frontend/package-lock.json

@@ -10310,6 +10310,12 @@
       "integrity": "sha1-Ywn04OX6kT7BxpMHrjZLSzd8nns=",
       "dev": true
     },
+    "node_modules/picocolors": {
+      "version": "0.2.1",
+      "resolved": "https://registry.npmjs.org/picocolors/-/picocolors-0.2.1.tgz",
+      "integrity": "sha512-cMlDqaLEqfSaW8Z7N5Jw+lyIW869EzT73/F5lhtY9cLGoVxSXznfgfXMO0Z5K0o0Q2TkTXq+0KFsdnSe3jDViA==",
+      "dev": true
+    },
     "node_modules/picomatch": {
       "version": "2.2.2",
       "resolved": "https://registry.npmjs.org/picomatch/-/picomatch-2.2.2.tgz",
@@ -10409,14 +10415,13 @@
       }
     },
     "node_modules/postcss": {
-      "version": "7.0.35",
+      "version": "7.0.39",
-      "resolved": "https://registry.npmjs.org/postcss/-/postcss-7.0.35.tgz",
+      "resolved": "https://registry.npmjs.org/postcss/-/postcss-7.0.39.tgz",
-      "integrity": "sha512-3QT8bBJeX/S5zKTTjTCIjRF3If4avAT6kqxcASlTWEtAFCb9NH0OUxNDfgZSWdP5fJnBYCMEWkIFfWeugjzYMg==",
+      "integrity": "sha512-yioayjNbHn6z1/Bywyb2Y4s3yvDAeXGOyxqD+LnVOinq6Mdmd++SW2wUNVzavyyHxd6+DxzWGIuosg6P1Rj8uA==",
       "dev": true,
       "dependencies": {
-        "chalk": "^2.4.2",
+        "picocolors": "^0.2.1",
-        "source-map": "^0.6.1",
+        "source-map": "^0.6.1"
-        "supports-color": "^6.1.0"
       },
       "engines": {
         "node": ">=6.0.0"
@@ -11070,18 +11075,6 @@
         "node": ">=0.10.0"
       }
     },
-    "node_modules/postcss/node_modules/supports-color": {
-      "version": "6.1.0",
-      "resolved": "https://registry.npmjs.org/supports-color/-/supports-color-6.1.0.tgz",
-      "integrity": "sha512-qe1jfm1Mg7Nq/NSh6XE24gPXROEVsWHxC1LIx//XNlD9iw7YZQGjZNjYN7xGaEG6iKdA8EtNFW6R0gjnVXp+wQ==",
-      "dev": true,
-      "dependencies": {
-        "has-flag": "^3.0.0"
-      },
-      "engines": {
-        "node": ">=6"
-      }
-    },
     "node_modules/prelude-ls": {
       "version": "1.1.2",
       "resolved": "https://registry.npmjs.org/prelude-ls/-/prelude-ls-1.1.2.tgz",
@@ -23696,6 +23689,12 @@
       "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
+    },
     "picomatch": {
       "version": "2.2.2",
       "resolved": "https://registry.npmjs.org/picomatch/-/picomatch-2.2.2.tgz",
@@ -23770,14 +23769,13 @@
       "dev": true
     },
     "postcss": {
-      "version": "7.0.35",
+      "version": "7.0.39",
-      "resolved": "https://registry.npmjs.org/postcss/-/postcss-7.0.35.tgz",
+      "resolved": "https://registry.npmjs.org/postcss/-/postcss-7.0.39.tgz",
-      "integrity": "sha512-3QT8bBJeX/S5zKTTjTCIjRF3If4avAT6kqxcASlTWEtAFCb9NH0OUxNDfgZSWdP5fJnBYCMEWkIFfWeugjzYMg==",
+      "integrity": "sha512-yioayjNbHn6z1/Bywyb2Y4s3yvDAeXGOyxqD+LnVOinq6Mdmd++SW2wUNVzavyyHxd6+DxzWGIuosg6P1Rj8uA==",
       "dev": true,
       "requires": {
-        "chalk": "^2.4.2",
+        "picocolors": "^0.2.1",
-        "source-map": "^0.6.1",
+        "source-map": "^0.6.1"
-        "supports-color": "^6.1.0"
       },
       "dependencies": {
         "source-map": {
@@ -23785,15 +23783,6 @@
           "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.npmjs.org/supports-color/-/supports-color-6.1.0.tgz",
-          "integrity": "sha512-qe1jfm1Mg7Nq/NSh6XE24gPXROEVsWHxC1LIx//XNlD9iw7YZQGjZNjYN7xGaEG6iKdA8EtNFW6R0gjnVXp+wQ==",
-          "dev": true,
-          "requires": {
-            "has-flag": "^3.0.0"
-          }
         }
       }
     },