Use `find` instead of `filter` in `SaveChangesDsl`
Use `find` instead of `filter` in `SaveChangesDsl`

I'm hoping to remove the implementation from the macro directly. Using
`find` instead reduces the number of methods we'll have to depend on in
order to make this generic.

cascalheira/diesel,cascalheira/diesel,mcasper/diesel,sgrif/diesel,sgrif/diesel,mcasper/diesel,diesel-rs/diesel,diesel-rs/diesel