chore(deps): bump @shoelace-style/shoelace from 2.19.1 to 2.20.0 (#1136)

Bumps [@shoelace-style/shoelace](https://github.com/shoelace-style/shoelace) from 2.19.1 to 2.20.0.
- [Release notes](https://github.com/shoelace-style/shoelace/releases)
- [Commits](shoelace-style/shoelace@v2.19.1...v2.20.0)

---
updated-dependencies:
- dependency-name: "@shoelace-style/shoelace"
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]

frontend/package.json

@@ -64,7 +64,7 @@
   "dependencies": {
     "@lit/context": "^1.1.3",
     "@lit/task": "^1.0.2",
-    "@shoelace-style/shoelace": "^2.19.1",
+    "@shoelace-style/shoelace": "^2.20.0",
     "@types/google.visualization": "^0.0.74",
     "@vaadin/router": "^2.0.0",
     "firebase": "^11.2.0",