convertSimpleArgument converts everything to string

Could you please explain why `convertSimpleArgument` in `values.go` converts everything to `string`? If I understood correctly, it then breaks the result from `sanitize.SanitizeSQL` in `(*Conn).SanitizeForSimpleQuery`. I tried to make a simple test and the result is as expected – `int64` got converted to `string`

Read values.go and trace convertSimpleArgument through (*Conn).SanitizeForSimpleQuery and sanitize.SanitizeSQL. Reproduce the reported int64-to-string conversion with the simple test described in the issue, then establish whether the conversion breaks the sanitized result and what behavior is expected.

Written by the indexing model from the issue text.