Vellum-ai

- Fixes a bug where nested nodes failed to resolve Lazy references of parent nodes
- Fix Prompt Node bug where empty arrays are assumed to be chat history
- `BaseWorkflow` now supports an optional `store` parameter for storing events and state snapshots
- New `EmptyStore` that does not store any events or state snapshots to help reduce memory usage

- Fixes a bug preventing Prompt Nodes from running
- Fixes display for Prompt node inputs
- Adds `UnknownParentContext` to be forward compatible with any future parent context

- Fix a bug with Guardrail node's handling of the log output
- Fix a bug that prevented Workflows with constants values on the left hand of an expression fail to initialize
- Exposes a new `.prompts.pull()` method for pulling prompts from the Vellum API

- Fixes bug that prevented the use of optional inputs
- Fixes a bug that caused deeply nested InlinePromptNode's to hang

- Fixes a bug preventing nodes with guardrail nodes outputs from initializing
- Added support for code generation for VPC customers

- Fixed issue with escaped characters in Code Nodes