[agent] Prepare v1.5.5 release (#206)

## Which problem is this PR solving?
Prepares the 1.5.5 honeycomb kubernetes agent

## Short description of the changes
- Update chart version to 1.5.5
- Add changelog entry

charts/honeycomb/CHANGELOG.md

@@ -1,5 +1,10 @@
 # Honeycomb Kubernetes Agent Helm Chart Changelog
 
+## Honeycomb Kubernetes Agent v1.5.5
+
+- Bump kubernetes agent version to [2.5.6](https://github.com/honeycombio/honeycomb-kubernetes-agent/releases/tag/v2.5.6) (#205)
+    - Add support for building sample keys from integer fields
+
 ## Honeycomb Kubernetes Agent v1.5.4
 
 - Bump kubernetes agent version to [2.5.5](https://github.com/honeycombio/honeycomb-kubernetes-agent/releases/tag/v2.5.5) (#148)

charts/honeycomb/Chart.yaml

@@ -1,7 +1,7 @@
 apiVersion: v2
 name: honeycomb
 description: Honeycomb Kubernetes Agent
-version: 1.5.4
+version: 1.5.5
 appVersion: 2.5.6
 keywords:
   - observability