Bump elastic-transport from 8.13.1 to 8.15.0

Bumps [elastic-transport](https://github.com/elastic/elastic-transport-python) from 8.13.1 to 8.15.0.
- [Release notes](https://github.com/elastic/elastic-transport-python/releases)
- [Changelog](https://github.com/elastic/elastic-transport-python/blob/v8.15.0/CHANGELOG.md)
- [Commits](elastic/elastic-transport-python@v8.13.1...v8.15.0)

---
updated-dependencies:
- dependency-name: elastic-transport
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

requirements.txt

@@ -366,7 +366,7 @@ easy-thumbnails==2.9
     #   djangocms-frontend
     #   djangocms-picture
     #   froide
-elastic-transport==8.13.1
+elastic-transport==8.15.0
     # via elasticsearch
 elasticsearch==8.15.1
     # via