source-postgres: exclude temp tables from discovery

Filters out temporary and unlogged tables during discovery. These tables cause
validation to fail because they cannot be added to publications. The filtering
is done based on the `pg_class.relpersistence` values, described in the docs:
https://www.postgresql.org/docs/current/catalog-pg-class.html#CATALOG-PG-CLASS

source-postgres/discovery.go

@@ -355,6 +355,8 @@ const queryDiscoverTables = `
   JOIN pg_catalog.pg_namespace n ON (n.oid = c.relnamespace)
   WHERE n.nspname NOT IN ('pg_catalog', 'pg_internal', 'information_schema', 'catalog_history', 'cron', 'pglogical')
     AND NOT c.relispartition
+    -- exclude temporary tables ('t') and unlogged tables ('u')
+    AND c.relpersistence = 'p'
     AND c.relkind IN ('r', 'p');` // 'r' means "Ordinary Table" and 'p' means "Partitioned Table"
 
 func getTables(ctx context.Context, conn *pgx.Conn, selectedSchemas []string) ([]*sqlcapture.DiscoveryInfo, error) {