Bump bootstrap from 3.3.6 to 5.3.3

Bumps [bootstrap](https://github.com/twbs/bootstrap) from 3.3.6 to 5.3.3.
- [Release notes](https://github.com/twbs/bootstrap/releases)
- [Commits](twbs/bootstrap@v3.3.6...v5.3.3)

---
updated-dependencies:
- dependency-name: bootstrap
  dependency-type: direct:development
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <[email protected]>

package.json

@@ -23,7 +23,7 @@
   "homepage": "https://github.com/freifunkh/fnorden.net#readme",
   "devDependencies": {
     "@fortawesome/fontawesome-free": "^6.7.1",
-    "bootstrap": "^3.4.1",
+    "bootstrap": "^5.3.3",
     "jquery": "^3.7.1",
     "leaflet": "^1.9.4",
     "less": "^4.2.1"