Removing unnecessary validation code

I wrote test_swagger_yaml before I realised I could
validate the API with apispec directly.

docs/test_swagger_yaml.py

@@ -1,16 +0,0 @@
-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}")