Fix redis consumers crashing due to relative path error

Specify absolute path to openapi_beta.yaml in routes.py

Consumers use a different working directory /opt/tildes/consumers

tildes/tildes/routes.py

@@ -16,6 +16,9 @@ from tildes.resources.topic import topic_by_id36
 from tildes.resources.user import user_by_username
 
 
+OPENAPI_YAML_FILE = "/opt/tildes/openapi_beta.yaml"
+
+
 def includeme(config: Configurator) -> None:
     """Set up application routes."""
     config.add_route("home", "/")
@@ -130,7 +133,7 @@ def includeme(config: Configurator) -> None:
 
     # Routes for the JSON API
     # We also provide a path for the full spec and the built-in swagger UI explorer
-    config.pyramid_openapi3_spec("openapi_beta.yaml", route="/api/beta/openapi.yaml")
+    config.pyramid_openapi3_spec(OPENAPI_YAML_FILE, route="/api/beta/openapi.yaml")
     config.pyramid_openapi3_add_explorer(route="/api/beta/ui")
 
     with config.route_prefix_context("/api/beta"):