Allow relative assets in rust > 1.88 (#4658)

* Allow relative assets in rust > 1.88 and assets outside of the crate in
binary crates

* undo changes to assets outside of the crate

* don't use relative assets in examples

packages/manganis/manganis-macro/Cargo.toml

@@ -15,7 +15,7 @@ proc-macro = true
 # be careful with dependencies you add here - these need to get compiled for the proc macro and therefore
 # prevent the main code from compiling!
 [dependencies]
-proc-macro2 = { workspace = true }
+proc-macro2 = { workspace = true, features = ["span-locations"] }
 quote = { workspace = true }
 syn = { workspace = true, features = ["full", "extra-traits"] }
 manganis-core = { workspace = true }