build(deps): bump php-opencloud/openstack from 3.14.0 to 3.15.0

Bumps [php-opencloud/openstack](https://github.com/php-opencloud/openstack) from 3.14.0 to 3.15.0.
- [Release notes](https://github.com/php-opencloud/openstack/releases)
- [Commits](php-opencloud/openstack@v3.14.0...v3.15.0)

---
updated-dependencies:
- dependency-name: php-opencloud/openstack
  dependency-version: 3.15.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]

composer.json

@@ -42,7 +42,7 @@
 		"pear/archive_tar": "^1.4.9",
 		"pear/pear-core-minimal": "^1.10",
 		"php-http/guzzle7-adapter": "^1.1.0",
-		"php-opencloud/openstack": "^3.14",
+		"php-opencloud/openstack": "^3.15",
 		"phpseclib/phpseclib": "^2.0.45",
 		"pimple/pimple": "^3.6.0",
 		"psr/clock": "^1.0",