[BUG][rust-axum] Doc tests fail due to invalid should_panic attribute

Bug Report Checklist

• Have you provided a full/minimal spec to reproduce the issue?
• Have you validated the input using an OpenAPI validator (example)?
• Have you tested with the latest master to confirm the issue still exists?
• Have you searched for related issues/PRs?
• What's the actual output vs expected output?
• [Optional] Sponsorship to speed up the bug fix or feature request (example)

Description

Doc tests of code generated with rust-axum generator fail since Rust 1.80.0 because of a bug in modules/openapi-generator/src/main/resources/rust-axum/types.mustache

openapi-generator version

7.8.0

Not a regression I think but the Rust toolchain has become more restrictive (it didn't fail with Rust 1.77.1)

OpenAPI declaration file content or url

Not applicable

Generation Details

$openapi_cli generate \
        -i "${api_spec}" \
        -o "${out_dir}" \
        -g rust-axum \
        --additional-properties=packageName="$package_name" \
        --name-mappings type=type_property \
        --openapi-normalizer FILTER="operationId:${route_filter}"

Steps to reproduce

Generate rust-axum, execute cargo test

Related issues/PRs

Didn't find anytghin

Suggest a fix

--- a/openapi-generator/templates/rust-axum/types.mustache
+++ b/openapi-generator/templates/rust-axum/types.mustache
@@ -175,7 +175,7 @@ impl<T> Nullable<T> {
     /// assert_eq!(x.expect("the world is ending"), "value");
     /// ```
     ///
-    /// ```{.should_panic}
+    /// ```should_panic
     /// # use {{{externCrateName}}}::types::Nullable;
     ///
     /// let x: Nullable<&str> = Nullable::Null;
@@ -210,7 +210,7 @@ impl<T> Nullable<T> {
     /// assert_eq!(x.unwrap(), "air");
     /// ```
     ///
-    /// ```{.should_panic}
+    /// ```should_panic
     /// # use {{{externCrateName}}}::types::Nullable;
     ///
     /// let x: Nullable<&str> = Nullable::Null;

I'll create a pull request

Start in modules/openapi-generator/src/main/resources/rust-axum/types.mustache, focusing on the Nullable documentation examples identified in the report. Generate a rust-axum project with the shown command and run cargo test to reproduce the failure. Done means the generated doc tests pass on Rust 1.80 and later.