Bump bootstrap from 3.3.7 to 5.1.3

Bumps [bootstrap](https://github.com/twbs/bootstrap) from 3.3.7 to 5.1.3.
- [Release notes](https://github.com/twbs/bootstrap/releases)
- [Commits](twbs/bootstrap@v3.3.7...v5.1.3)

---
updated-dependencies:
- dependency-name: bootstrap
  dependency-version: 5.1.3
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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Author: dependabot[bot]