v1.21.0

## New Features

- Conditional Nodes - Now every node can optionally have a condition input toggling whether the node runs
- {{tokens}} can be escaped by doing {{{token}}}
- New node: Document - Load documents such as PDF files into rivet for passing to e.g. Anthropic
- New node: Play Audio - Plays audio data directly!
- New convenience node: Chat Loop - Easily set up a chat loop with user input!
- New convenience node: Read All Files - Read all files in a directory!
- New node: To Markdown Table - Converts an array of objects into a markdown table!
- New node: Cron - Runs a graph at a specified time or interval!
- Anthropic Plugin: Support for PDF processing!
- Anthropic Plugin: Support for Citations!
- Anthropic Plugin: Endpoint can be overriden in the settings or the Chat Anthropic node
- Google Plugin: Support for all Gemini 2.0 models!
- Google Plugin: Support for using a Generative AI API Key instead of application credentials, the new preferred method
- OpenAI: Support for o1 and o3-mini models!
- OpenAI: Support for GPT 4o Audio! Get output as audio!
- OpenAI: Support for predicted outputs!
- OpenAI: Use the server for token counts instead of calculating them locally

## Changes & Fixes

- Added DocumentDataValue type
- Added DirectoryBrowserEditorDefinition type
- User input nodes are now handled like all other nodes, and any node can call `context.requestUserInput` to request user input.
- `RivetUIContext` now has access to the `nativeApi` configured.
- Added setting to throttle chat node updates - can improve performance