Bump select2 from 4.0.4 to 4.0.6 in /pgadmin

Bumps [select2](https://github.com/select2/select2) from 4.0.4 to 4.0.6.
- [Release notes](https://github.com/select2/select2/releases)
- [Changelog](https://github.com/select2/select2/blob/develop/CHANGELOG.md)
- [Commits](select2/select2@4.0.4...4.0.6)

---
updated-dependencies:
- dependency-name: select2
  dependency-type: direct:production
...

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

Author: dependabot[bot]