Bump @adobe/css-tools from 4.2.0 to 4.3.1 in /demo

Bumps [@adobe/css-tools](https://github.com/adobe/css-tools) from 4.2.0 to 4.3.1.
- [Changelog](https://github.com/adobe/css-tools/blob/main/History.md)
- [Commits](https://github.com/adobe/css-tools/commits)

---
updated-dependencies:
- dependency-name: "@adobe/css-tools"
  dependency-type: indirect
...

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

demo/yarn.lock

@@ -3,9 +3,9 @@
 
 
 "@adobe/css-tools@^4.0.1":
-  version "4.2.0"
-  resolved "https://registry.yarnpkg.com/@adobe/css-tools/-/css-tools-4.2.0.tgz#e1a84fca468f4b337816fcb7f0964beb620ba855"
-  integrity sha512-E09FiIft46CmH5Qnjb0wsW54/YQd69LsxeKUOWawmws1XWvyFGURnAChH0mlr7YPFR1ofwvUQfcL0J3lMxXqPA==
+  version "4.3.1"
+  resolved "https://registry.yarnpkg.com/@adobe/css-tools/-/css-tools-4.3.1.tgz#abfccb8ca78075a2b6187345c26243c1a0842f28"
+  integrity sha512-/62yikz7NLScCGAAST5SHdnjaDJQBDq0M2muyRTpf2VQhw6StBg2ALiu73zSJQ4fMVLA+0uBhBHAle7Wg+2kSg==
 
 "@babel/helper-string-parser@^7.21.5":
   version "7.21.5"