Hardcode bun version (#494)

pynecone/constants.py

@@ -68,7 +68,7 @@ API_URL = "http://localhost:8000"
 # The default path where bun is installed.
 BUN_PATH = "$HOME/.bun/bin/bun"
 # Command to install bun.
-INSTALL_BUN = "curl https://bun.sh/install | bash"
+INSTALL_BUN = "curl -fsSL https://bun.sh/install | bash -s -- bun-v0.5.5"
 # Default host in dev mode.
 BACKEND_HOST = "0.0.0.0"
 # The default timeout when launching the gunicorn server.