Add uncategorized PRs to changelog (#1270)

.github/changelog_configuration.json

@@ -1,5 +1,5 @@
 {
-  "template": "${{CHANGELOG}}",
+  "template": "${{CHANGELOG}}\n\n<details>\n<summary>Uncategorized</summary>\n\n${{UNCATEGORIZED}}\n</details>",
   "pr_template": "- ${{TITLE}} #${{NUMBER}}",
   "empty_template": "- no changes",
   "categories": [
@@ -20,4 +20,4 @@
   "tag_resolver": {
     "method": "semver"
   }
-}
+}