build(deps): bump splunk-sdk from 1.6.19 to 1.6.20 (#168)

Bumps [splunk-sdk](https://github.com/splunk/splunk-sdk-python) from 1.6.19 to 1.6.20.
- [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@1.6.19...1.6.20)

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

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Author: dependabot[bot]