Use Exact operator instead of Caret as default

[ologbonowiwi]

Not always we want Carot operator to be the default. There are cases such as in rust-lang/rustfmt#6066, as if user sets "1.0.0", "1.1.0" should not work as user set an implicitly exact operator.

Alternatively, we could create a a param to set ourselves the default operator to be used. I'm this way it's not be a major change but still get the benefits of customizing varying on software specific needs