Add Clickhouse to demo page language dropdown

Author: nene

static/index.html

@@ -59,6 +59,7 @@ <h3 style="margin: 0.5rem 0">Options</h3>
               <!-- dialects -->
               <option value="redshift">AWS Redshift</option>
               <option value="bigquery">BigQuery</option>
+              <option value="clickhouse">Clickhouse</option>
               <option value="db2">DB2</option>
               <option value="db2i">DB2 for IBM i</option>
               <option value="duckdb">DuckDB</option>