chore(release): prepare for v0.3.1 (#145)

## [0.3.1] - 2026-05-29

### 🐛 Bug Fixes

- Set service.instance.id for unique instance label (#144)

<!-- generated by git-cliff -->

---

**Note:** Please use **Squash Merge** when merging this PR.

Reviewed-on: https://gitea.unbound.se/shiny/otelsetup/pulls/145
Co-authored-by: Unbound Releaser <releaser@unbound.se>
Co-committed-by: Unbound Releaser <releaser@unbound.se>

.version

@@ -1,3 +1,3 @@
 {
-  "version": "v0.3.0"
+  "version": "v0.3.1"
 }

CHANGELOG.md

@@ -2,6 +2,12 @@
 
 All notable changes to this project will be documented in this file.
 
+## [0.3.1] - 2026-05-29
+
+### 🐛 Bug Fixes
+
+- Set service.instance.id for unique instance label (#144)
+
 ## [0.3.0] - 2026-05-26
 
 ### 🚀 Features