Added support for .wesl files to the regex pattern for examples (#19178)

## Objective

[Shaders / Material -
WESL](https://bevyengine.org/examples-webgpu/shaders/shader-material-wesl/)
example doesn't have a WESL file tab


## Solution

 Added wesl to regex

---------

Co-authored-by: Stepan Urazov <[email protected]>

Author: atlasgorn

tools/example-showcase/src/main.rs

@@ -773,9 +773,7 @@ fn parse_examples() -> Vec<Example> {
             let technical_name = val.get("name").unwrap().as_str().unwrap().to_string();
 
             let source_code = fs::read_to_string(val["path"].as_str().unwrap()).unwrap();
-            let shader_regex =
-                Regex::new(r"(shaders\/\w+\.wgsl)|(shaders\/\w+\.frag)|(shaders\/\w+\.vert)")
-                    .unwrap();
+            let shader_regex = Regex::new(r"shaders\/\w+\.(wgsl|frag|vert|wesl)").unwrap();
 
             // Find all instances of references to shader files, and keep them in an ordered and deduped vec.
             let mut shader_paths = vec![];