Bump open-telemetry/exporter-otlp from 1.0.4 to 1.2.0

Bumps [open-telemetry/exporter-otlp](https://github.com/opentelemetry-php/exporter-otlp) from 1.0.4 to 1.2.0.
- [Release notes](https://github.com/opentelemetry-php/exporter-otlp/releases)
- [Commits](opentelemetry-php/exporter-otlp@1.0.4...1.2.0)

---
updated-dependencies:
- dependency-name: open-telemetry/exporter-otlp
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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