Fix typo in AGENTS.md regarding tests (#41)

Author: miluchen

AGENTS.md

@@ -6,7 +6,7 @@ The following is a guide for working with this project.
 
 ## Project structure
 
-This Python project uses the `uv` package manager. You should always use `uv` to install dependencies, run the agent, and run testss
+This Python project uses the `uv` package manager. You should always use `uv` to install dependencies, run the agent, and run tests.
 
 All app-level code is in the `src/` directory. In general, simple agents can be constructed with a single `agent.py` file. Additional files can be added, but you must retain `agent.py` as the entrypoint (see the associated Dockerfile for how this is deployed).