[Automation] Bump product version numbers

[elastic-observability-automation]

Bump release versions in the config/versions.yml

Update config/versions.yml edot-node 1.6.0

change detected: * key "$.versioning_systems.edot-node.current" updated from "1.5.0" to "1.6.0", in file "config/versions.yml"

v1.6.0

## Changelog

### Features and enhancements

* Add support for `ELASTIC_OTEL_OPAMP_HEADERS` environment variable for setting headers for OpAMP requests. This typically would be used to specify authorization for a given `ELASTIC_OTEL_OPAMP_ENDPOINT`, e.g.: `export ELASTIC_OTEL_OPAMP_HEADERS="Authorization=ApiKey sekrit"`. [#1069](https://github.com/elastic/elastic-otel-node/issues/1069)

* HTTP exporters now accept TLS configuration via the env vars `OTEL_EXPORTER_OTLP_CERTIFICATE`, `OTEL_EXPORTER_OTLP_CLIENT_KEY` and `OTEL_EXPORTER_OTLP_CLIENT_CERTIFICATE`. The signal specific vars (`OTEL_EXPORTER_OTLP_TRACES_CERTIFICATE`, ...) are also taken into account.

* Prepend EDOT Node.js product identifier in the `user-agent` for all HTTP and GRPC exporters. ([#1104](https://github.com/elastic/elastic-otel-node/pull/1104))

* Switch back to the upstream resource detector `@opentelemetry/resource-detector-gcp` which covers more environments thanks to Google's [contribution](https://github.com/open-telemetry/opentelemetry-js-contrib/pull/3007).

* Add support for dynamic configuration of the sampling rate of the default logger via the `sampling_rate` variable in Central Configuration. [#1070](https://github.com/elastic/elastic-otel-node/pull/1070)

  While this is supported in the EDOT Node.js SDK, it will only be present in
  the "Agent Configuration" UI of Kibana version 9.3 and later.

### Fixes

* Update to latest `@opentelemetry/*` dependencies ([#1104](https://github.com/elastic/elastic-otel-node/pull/1104)), which includes a couple of fixes:
    * a bug in `@opentelemetry/[email protected]` prevented to set the `user-agent` header in metadata. A [change in the exporter configuration](https://github.com/open-telemetry/opentelemetry-js/pull/5928) fixed it.
    * the context manager and propagation setup is the first thing at the start of the SDK. This prevents detectors from [leaking telemetry](https://github.com/open-telemetry/opentelemetry-js-contrib/issues/2320) since they get the right context.

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[README](https://github.com/elastic/elastic-otel-node/tree/main/packages/opentelemetry-node#readme) | [Full Release Notes](https://github.com/elastic/elastic-otel-node/blob/main/docs/release-notes/index.md) | [Breaking Changes](https://github.com/elastic/elastic-otel-node/blob/main/docs/release-notes/breaking-changes.md)

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