webui: upgrade bootstrap to version 3.4.1

CHANGELOG.md

@@ -19,6 +19,7 @@ and since Bareos version 20 this project adheres to [Semantic Versioning](https:
 -  dird: add prev and new jobid variables [PR #1518]
 - build: switch from FreeBSD 13.1 to 13.2 [PR #1525]
 - plugin-fd: allow fd plugins to (re-)set since-time and disable/re-enable timestamp/accurate checks [PR #1534]
+- webui: upgrade bootstrap to version 3.4.1 [PR #1551]
 
 ### Fixed
 - stored: fix incoherent meta data when concurrently writing to the same volume [PR #1514]
@@ -567,4 +568,5 @@ and since Bareos version 20 this project adheres to [Semantic Versioning](https:
 [PR #1519]: https://github.com/bareos/bareos/pull/1519
 [PR #1525]: https://github.com/bareos/bareos/pull/1525
 [PR #1534]: https://github.com/bareos/bareos/pull/1534
+[PR #1551]: https://github.com/bareos/bareos/pull/1551
 [unreleased]: https://github.com/bareos/bareos/tree/master