message: Server allow `unused_variables` in `serverSerializeResponse` and `serverParseRequest`
  Note the attribute is added unconditionally, even if it might not be
  always needed in the generated code.
diff: @@ -315,15 +315,13 @@ private class ServerHttpProtocolImplGenerator(
  val fnName = "parse_${operationShape.id.name.toSnakeCase()}_request"
  val inputShape = operationShape.inputShape(model)
  val inputSymbol = symbolProvider.toSymbol(inputShape)
  - val includedMembers = httpBindingResolver.requestMembers(operationShape, HttpLocation.DOCUMENT)
  - val unusedVars = if (includedMembers.isEmpty()) "##[allow(unused_variables)] " else ""
  return RuntimeType.forInlineFun(fnName, operationDeserModule) {
  Attribute.Custom("allow(clippy::unnecessary_wraps)").render(it)
  it.rustBlockTemplate(
  """
  pub async fn $fnName<B>(
  - ${unusedVars}request: &mut #{AxumCore}::extract::RequestParts<B>
  + ##[allow(unused_variables)] request: &mut #{AxumCore}::extract::RequestParts<B>
  ) -> std::result::Result<
  #{I},
  #{SmithyRejection}
  @@ -352,6 +350,7 @@ private class ServerHttpProtocolImplGenerator(
  val fnName = "serialize_${operationShape.id.name.toSnakeCase()}_response"
  val outputShape = operationShape.outputShape(model)
  val outputSymbol = symbolProvider.toSymbol(outputShape)
  +
  return RuntimeType.forInlineFun(fnName, operationSerModule) {
  Attribute.Custom("allow(clippy::unnecessary_wraps)").render(it)
  @@ -359,7 +358,14 @@ private class ServerHttpProtocolImplGenerator(
  // However we currently always take ownership here, but worth noting in case in the future we want
  // to generate different signatures for streaming vs non-streaming for some reason.
  it.rustBlockTemplate(
  - "pub fn $fnName(output: #{O}) -> std::result::Result<#{AxumCore}::response::Response, #{SmithyRejection}>",
  + """
  + pub fn $fnName(
  + ##[allow(unused_variables)] output: #{O}
  + ) -> std::result::Result<
  + #{AxumCore}::response::Response,
  + #{SmithyRejection}
  + >
  + """.trimIndent(),
  *codegenScope,
  "O" to outputSymbol,
  ) {
  