Python dependency: Bump postcss from 8.4.24 to 8.4.31 in /web (#6819)

Bumps [postcss](https://github.com/postcss/postcss) from 8.4.24 to 8.4.31.
- [Release notes](https://github.com/postcss/postcss/releases)
- [Changelog](https://github.com/postcss/postcss/blob/main/CHANGELOG.md)
- [Commits](postcss/postcss@8.4.24...8.4.31)

---
updated-dependencies:
- dependency-name: postcss
  dependency-type: direct:production
...

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

web/package.json

@@ -137,7 +137,7 @@
     "pathfinding": "^0.4.18",
     "paths-js": "^0.4.9",
     "popper.js": "^1.16.1",
-    "postcss": "^8.2.15",
+    "postcss": "^8.4.31",
     "raf": "^3.4.1",
     "rc-dock": "^3.2.9",
     "react": "^17.0.1",

web/yarn.lock

@@ -11812,7 +11812,7 @@ __metadata:
   languageName: node
   linkType: hard
 
-"postcss@npm:^8.2.15, postcss@npm:^8.4.21, postcss@npm:^8.4.24":
+"postcss@npm:^8.4.21, postcss@npm:^8.4.24":
   version: 8.4.24
   resolution: "postcss@npm:8.4.24"
   dependencies:
@@ -11823,6 +11823,17 @@ __metadata:
   languageName: node
   linkType: hard
 
+"postcss@npm:^8.4.31":
+  version: 8.4.31
+  resolution: "postcss@npm:8.4.31"
+  dependencies:
+    nanoid: ^3.3.6
+    picocolors: ^1.0.0
+    source-map-js: ^1.0.2
+  checksum: 1d8611341b073143ad90486fcdfeab49edd243377b1f51834dc4f6d028e82ce5190e4f11bb2633276864503654fb7cab28e67abdc0fbf9d1f88cad4a0ff0beea
+  languageName: node
+  linkType: hard
+
 "precond@npm:^0.2.3":
   version: 0.2.3
   resolution: "precond@npm:0.2.3"
@@ -13168,7 +13179,7 @@ __metadata:
     pathfinding: ^0.4.18
     paths-js: ^0.4.9
     popper.js: ^1.16.1
-    postcss: ^8.2.15
+    postcss: ^8.4.31
     postcss-loader: ^7.1.0
     process: ^0.11.10
     prop-types: ^15.7.2