Using time.Time with zero value results in "dateTime overflow" error.

### Issue description
We're using `jmoiron/sqlx` library to insert data to CH database.
When I switched project to use `clickhouse-go/v2`, inserting object with field `time.Time` with zero value (0001-01-01 00:00:00 +0000 UTC) results in dateTime overflow error.
In previous v1, it was inserting the beginning of Unix timestamp.

### Example code
```go
type Event struct {
EventAt time.Time `db:"event_at"` // this one is filled with correct data
DifferentEventAt time.Time `db:"different_event_at"` // this one is untouched, so zero time.Time value remains
}
```

### Error log
```
clickhouse: dateTime overflow. different_event_at must be between 1970-01-01 00:00:00 and 2105-12-31 23:59:59
```

### Configuration
*OS:*
macOS M1

*Interface:*
`golang.yandex/hasql/sqlx` along with `github.com/jmoiron/sqlx`

*Driver version:*
v2.5.1

*Go version:*
1.19.4

*ClickHouse Server version:*
21.5.7.9 running on Docker

No source file or test is named. Start by reproducing the zero-value time.Time insert with clickhouse-go/v2 and compare it with the previous v1 behavior; trace the dateTime encoding path and add regression coverage once the expected handling is decided.

Written by the indexing model from the issue text.