Bump postcss from 8.3.0 to 8.3.1 in /build/javascript (#1089)

Bumps [postcss](https://github.com/postcss/postcss) from 8.3.0 to 8.3.1.
- [Release notes](https://github.com/postcss/postcss/releases)
- [Changelog](https://github.com/postcss/postcss/blob/main/CHANGELOG.md)
- [Commits](https://github.com/postcss/postcss/compare/8.3.0...8.3.1)

---
updated-dependencies:
- dependency-name: postcss
  dependency-type: direct:development
  update-type: version-update:semver-patch
...

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Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

build/javascript/package-lock.json

@@ -1410,9 +1410,9 @@
       }
     },
     "postcss": {
-      "version": "8.3.0",
-      "resolved": "https://registry.npmjs.org/postcss/-/postcss-8.3.0.tgz",
-      "integrity": "sha512-+ogXpdAjWGa+fdYY5BQ96V/6tAo+TdSSIMP5huJBIygdWwKtVoB5JWZ7yUd4xZ8r+8Kvvx4nyg/PQ071H4UtcQ==",
+      "version": "8.3.1",
+      "resolved": "https://registry.npmjs.org/postcss/-/postcss-8.3.1.tgz",
+      "integrity": "sha512-9qH0MGjsSm+fjxOi3GnwViL1otfi7qkj+l/WX5gcRGmZNGsIcqc+A5fBkE6PUobEQK4APqYVaES+B3Uti98TCw==",
       "dev": true,
       "requires": {
         "colorette": "^1.2.2",

build/javascript/package.json

@@ -15,7 +15,7 @@
   },
   "devDependencies": {
     "cssnano": "^5.0.5",
-    "postcss": "^8.3.0",
+    "postcss": "^8.3.1",
     "postcss-cli": "^8.3.1"
   },
   "snowpack": {