Generate release notes from PR labels (#265)

This change enables automatic release notes from labels. It also
enforces a changelog label for all PRs.

Categorizing changes will make it easier for users to understand what
changed in each release.

<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->

## Summary by CodeRabbit

## Chores
* Implemented automated changelog categorization and pull request label
enforcement to organize release notes into semantic sections (Added,
Changed, Fixed, Deprecated, Removed, Security, Dependencies) for
improved clarity in future releases.

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Signed-off-by: Philip Laine <philip.laine@gmail.com>

.github/dependabot.yaml

@@ -5,6 +5,8 @@ updates:
     schedule:
       interval: "weekly"
     open-pull-requests-limit: 15
+    labels:
+      - "changelog/ignore"
     groups:
       github-actions:
         patterns:
@@ -15,6 +17,8 @@ updates:
     schedule:
       interval: "weekly"
     open-pull-requests-limit: 15
+    labels:
+      - "changelog/dependencies"
     groups:
       k8s:
         patterns:
@@ -25,6 +29,8 @@ updates:
     schedule:
       interval: "weekly"
     open-pull-requests-limit: 15
+    labels:
+      - "changelog/ignore"
     groups:
       gomod-e2e:
         patterns: