Use dep: prefix to remove implicit feature flags

[bouzuya]

This Pull Request updates the project to use the dep: prefix.

By using the dep: prefix, it removes the implicit feature flags that are automatically enabled by optional dependencies. For more details about the dep: prefix, see https://doc.rust-lang.org/cargo/reference/features.html#optional-dependencies.

If these implicit feature flags were intentional, this Pull Request is not appropriate and should be closed. If they were not, merging this Pull Request will ensure that only explicitly defined feature flags are provided.

[Keats]

It's unlikely to be causing an issue in practice but that would be a breaking change, so for v11