fixed warning of resolver = "1"

[AneesHl]

Running cargo build causes a warning the following warning:

$ cargo build
warning: virtual workspace defaulting to `resolver = "1"` despite one or more workspace members being on edition 2021 which implies `resolver = "2"`
note: to keep the current resolver, specify `workspace.resolver = "1"` in the workspace root's manifest
note: to use the edition 2021 resolver, specify `workspace.resolver = "2"` in the workspace root's manifest
note: for more details see https://doc.rust-lang.org/cargo/reference/resolver.html#resolver-versions

[oowekyala]

I think we should remove the workspace structure which would be a more long-term fix