Bump github.com/openzipkin/zipkin-go from 0.2.5 to 0.3.0 in /exporter…

…s/zipkin (#2337)

* Bump github.com/openzipkin/zipkin-go in /exporters/zipkin

Bumps [github.com/openzipkin/zipkin-go](https://github.com/openzipkin/zipkin-go) from 0.2.5 to 0.3.0.
- [Release notes](https://github.com/openzipkin/zipkin-go/releases)
- [Commits](openzipkin/zipkin-go@v0.2.5...v0.3.0)

---
updated-dependencies:
- dependency-name: github.com/openzipkin/zipkin-go
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

* Auto-fix go.sum changes in dependent modules

* go mod tidy in example/zipkin

* Revert internal/tools changes

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: MrAlias <MrAlias@users.noreply.github.com>
Co-authored-by: Tyler Yahn <codingalias@gmail.com>