Bump postcss from 8.3.3 to 8.3.4 in /build/javascript (#1104)

Bumps [postcss](https://github.com/postcss/postcss) from 8.3.3 to 8.3.4.
- [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/8.3.3...8.3.4)

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

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

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

build/javascript/package-lock.json

@@ -1415,9 +1415,9 @@
       }
     },
     "postcss": {
-      "version": "8.3.3",
-      "resolved": "https://registry.npmjs.org/postcss/-/postcss-8.3.3.tgz",
-      "integrity": "sha512-gnXd9C4bGKevvlNFd80I8WfxHX+g6MR+W2h19PlDNHUuT9248rHTvCIDeZI3Hvs5mB3gzXiNDwVK3S153WJbZA==",
+      "version": "8.3.4",
+      "resolved": "https://registry.npmjs.org/postcss/-/postcss-8.3.4.tgz",
+      "integrity": "sha512-/tZY0PXExXXnNhKv3TOvZAOUYRyuqcCbBm2c17YMDK0PlVII3K7/LKdt3ScHL+hhouddjUWi+1sKDf9xXW+8YA==",
       "dev": true,
       "requires": {
         "colorette": "^1.2.2",

build/javascript/package.json

@@ -15,7 +15,7 @@
   },
   "devDependencies": {
     "cssnano": "^5.0.6",
-    "postcss": "^8.3.3",
+    "postcss": "^8.3.4",
     "postcss-cli": "^8.3.1"
   },
   "snowpack": {