json1 SQLite extension is not correctly detected in versions.json

[sebbacon]

Due to hasversion always being False for json1, it is never detected in this code path:

datasette/datasette/app.py

Lines 1106 to 1115 in 7d6d471

	for extension, testsql, hasversion in (
	("json1", "SELECT json('{}')", False),
	("spatialite", "SELECT spatialite_version()", True),
	):
	try:
	result = conn.execute(testsql)
	if hasversion:
	sqlite_extensions[extension] = result.fetchone()[0]
	else:
	sqlite_extensions[extension] = None