Return the correct non-generic enumerator for ClickHouseParameterCollection

[henkmollema]

A foreach loop uses the non-generic IEnumerator GetEnumerator(). This currently uses _parameters.GetEnumerator() which returns the enumerator of the dictionary, which returns KeyValuePair<string, ClickHouseParameter>'s rather than ClickHouseParameter's. This causes an error when using DynamicParameters with Dapper: https://github.com/DapperLib/Dapper/blob/ca00feeb5fafe5262166689c0bec2b80b53add4e/Dapper/DynamicParameters.cs#L194.