build(deps): bump splunk-sdk from 1.6.18 to 1.6.19 (#156)

Bumps [splunk-sdk](https://github.com/splunk/splunk-sdk-python) from 1.6.18 to 1.6.19.
- [Release notes](https://github.com/splunk/splunk-sdk-python/releases)
- [Changelog](https://github.com/splunk/splunk-sdk-python/blob/master/CHANGELOG.md)
- [Commits](splunk/splunk-sdk-python@1.6.18...1.6.19)

---
updated-dependencies:
- dependency-name: splunk-sdk
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>