Some basic validation for OpenAPI

I was getting unhelpful OpenAPI errors, this Python script makes it easier
to figure out where they come from.

docs/test_swagger_yaml.py

@@ -0,0 +1,15 @@
+import yaml
+with open("./build/swagger.yaml", "r") as f:
+    api = yaml.load(f)
+
+for path, methods in api["paths"].items():
+    for method, properties in methods.items():
+        try:
+            for k in ["responses", "description"]:
+                current_key = k
+                _ = properties[k]
+            for code, r in properties["responses"].items():
+                current_key = f"responses/{code}/description"
+                _ = r["description"]
+        except KeyError as e:
+            print(f"❌ {method} {path} has a problem: {e} from {current_key}")