`include_image!` now accepts expressions (#4521)

Closes https://github.com/emilk/egui/issues/4510

crates/egui/src/lib.rs

@@ -507,7 +507,7 @@ pub fn warn_if_debug_build(ui: &mut crate::Ui) {
 /// ```
 #[macro_export]
 macro_rules! include_image {
-    ($path: literal) => {
+    ($path:expr $(,)?) => {
         $crate::ImageSource::Bytes {
             uri: ::std::borrow::Cow::Borrowed(concat!("bytes://", $path)),
             bytes: $crate::load::Bytes::Static(include_bytes!($path)),