Bump guzzlehttp/guzzle in /examples/distributed-tracing/src (#722)

Bumps [guzzlehttp/guzzle](https://github.com/guzzle/guzzle) from 7.4.4 to 7.4.5.
- [Release notes](https://github.com/guzzle/guzzle/releases)
- [Changelog](https://github.com/guzzle/guzzle/blob/master/CHANGELOG.md)
- [Commits](guzzle/guzzle@7.4.4...7.4.5)

---
updated-dependencies:
- dependency-name: guzzlehttp/guzzle
  dependency-type: direct:production
...

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