Update to current version of near-sdk crate

[mikedotexe]

This project is using an outdated version of the near-sdk crate.
Install the latest version as shown here:
https://crates.io/crates/near-sdk

This will require updating Cargo.toml and fixing whatever issues seem to arise when building.
You may use this example as a decent reference for how things work in the more recent version of the crate.
https://github.com/near-examples/rust-counter