Depend on Datasette >= 0.48

Refs #15, refs simonw/datasette#938

setup.py

@@ -29,7 +29,7 @@ def get_long_description():
     packages=["datasette_cluster_map"],
     entry_points={"datasette": ["cluster_map = datasette_cluster_map"]},
     package_data={"datasette_cluster_map": ["static/datasette-cluster-map.js"]},
-    install_requires=["datasette"],
+    install_requires=["datasette>=0.48"],
     extras_require={"test": ["pytest", "pytest-asyncio", "httpx", "sqlite-utils"]},
     tests_require=["datasette-cluster-map[test]"],
 )