Update formatNamedParameters to not match parameters starting with digit

Using a query like:
query = "SELECT * FROM t WHERE create_at > CURRENT_DATE + CURRENT_TIME - time '01:30' LIMIT :limit";
Sequelize.query(query, null, {raw: true}, { limit: limit })
will fail due to "time '01:30'" where it will look for a parameter named '30'

lib/sql-string.js

@@ -143,7 +143,7 @@ SqlString.format = function(sql, values, timeZone, dialect) {
 }
 
 SqlString.formatNamedParameters = function(sql, values, timeZone, dialect) {
-  return sql.replace(/\:(\w+)/g, function (value, key) {
+  return sql.replace(/\:(?!\d)(\w+)/g, function (value, key) {
     if (values.hasOwnProperty(key)) {
       return SqlString.escape(values[key], false, timeZone, dialect)
     } else {