Bump the MSRV to 1.62 and using #[derive(Default)] on enums (#3304)

## Issue Addressed

N/A

## Proposed Changes

Since Rust 1.62, we can use `#[derive(Default)]` on enums. ✨ 

https://blog.rust-lang.org/2022/06/30/Rust-1.62.0.html#default-enum-variants

There are no changes to functionality in this PR, just replaced the `Default` trait implementation with `#[derive(Default)]`.

.github/workflows/local-testnet.yml

@@ -18,6 +18,9 @@ jobs:
     steps:
       - uses: actions/checkout@v1
 
+      - name: Get latest version of stable Rust
+        run: rustup update stable
+
       - name: Install ganache
         run: npm install ganache@latest --global