docs(changelog): note the workflow autowrap bugfix in 1.3.7 entry

PR #460 merged into main after the 1.3.7 version bump (#463) so the
in-tree CHANGELOG was missing it. Adds a "Fixed" subsection under the
1.3.7 entry that mirrors what ships in the GitHub Release notes / on
PyPI, plus the migration note for already-broken workflows.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: yeldarby

CHANGELOG.md

@@ -39,6 +39,25 @@ those actions are not exposed on the SDK or CLI — they live only in the
 Roboflow app's Trash view, which has an explicit confirmation dialog.
 Items left in Trash are cleaned up automatically after 30 days.
 
+### Fixed — Workflows created via SDK/CLI now execute successfully
+
+`Workspace.create_workflow()` and `roboflow workflow create --definition`
+auto-wrap bare workflow definitions in `{"specification": ...}` before
+POSTing to the backend, matching what the web app does
+([#460](https://github.com/roboflow/roboflow-python/pull/460)). Previously,
+the user-facing flat shape (`{version, inputs, steps, outputs}`) was sent
+verbatim, so `POST /infer/workflows/...` against the resulting workflow
+returned `HTTP 502` with `MalformedWorkflowResponseError: Workflow
+specification not found in Roboflow API response`.
+
+Workflows already wrapped (top-level `specification` key) are passed
+through unchanged. Non-workflow dicts and non-JSON strings are also
+passed through verbatim so custom payloads aren't second-guessed.
+
+> **Note:** workflows that were stored with the bare shape *before* this
+> fix will still 502 until re-saved. Run `roboflow workflow update
+> <url> --definition <file>` once per affected workflow to migrate.
+
 ### Changed — Image upload no longer re-encodes images
 
 `upload_image` now uploads original image bytes instead of re-encoding to