message: Remove `Sanity::new()` in msgpack_spec test and implement `Default` instead
diff: use polywrap_wasm_rs::{Context, Read, ReadDecoder, Write, WriteEncoder, WriteSizer};
  use std::collections::HashMap;
  -#[derive(Debug, Clone)]
  +#[derive(Debug, Clone, Default)]
  pub struct Sanity {
  nil: Option<String>,
  int8: i8,
  @@ -29,34 +29,6 @@ pub struct Sanity {
  }
  impl Sanity {
  - fn new() -> Self {
  - Self {
  - nil: None,
  - int8: 0,
  - int16: 0,
  - int32: 0,
  - int64: 0,
  - uint8: 0,
  - uint16: 0,
  - uint32: 0,
  - uint64: 0,
  - boolean: false,
  - opt_uint32: None,
  - opt_uint64: None,
  - opt_bool: None,
  - float32: 0.0,
  - float64: 0.0,
  - string: String::new(),
  - large_string: String::new(),
  - bytes: vec![],
  - large_bytes: vec![],
  - array: vec![],
  - large_string_array: vec![],
  - large_bytes_array: vec![],
  - map: HashMap::new(),
  - }
  - }
  -
  fn init(&mut self) -> Self {
  let huge_vec = vec!["web3api".to_string(); 10_000];
  let huge_string = huge_vec.join(",");
  @@ -441,9 +413,9 @@ impl Eq for Sanity {}
  #[test]
  fn serialize_and_deserialize() {
  - let mut sanity_input = Sanity::new();
  + let mut sanity_input = Sanity::default();
  let mut input = sanity_input.init();
  - let mut output = Sanity::new();
  + let mut output = Sanity::default();
  output
  .from_buffer(input.to_buffer().as_slice())
  .expect("Failed to to write output from buffer");
  @@ -452,9 +424,9 @@ fn serialize_and_deserialize() {
  #[test]
  fn serialize_and_deserialize_with_overflow() {
  - let mut sanity_input = Sanity::new();
  + let mut sanity_input = Sanity::default();
  let mut input = sanity_input.init();
  - let mut output = Sanity::new();
  + let mut output = Sanity::default();
  assert!(output
  .from_buffer_with_overflows(input.to_buffer().as_slice())
  .is_ok());
  @@ -462,9 +434,9 @@ fn serialize_and_deserialize_with_overflow() {
  #[test]
  fn throw_error_if_invalid_type_found() {
  - let mut sanity_input = Sanity::new();
  + let mut sanity_input = Sanity::default();
  let mut input = sanity_input.init();
  - let mut output = Sanity::new();
  + let mut output = Sanity::default();
  assert!(output
  .from_buffer_with_invalid_types(input.to_buffer().as_slice())
  .is_ok());
  