test: move image-converter tests to tests/

crates/adapters/image-converter/src/handler.rs

@@ -99,7 +99,3 @@ fn convert(bytes: Vec<u8>, format: Format) -> Result<Vec<u8>, String> {
         }
     }
 }
-
-#[cfg(test)]
-#[path = "tests/handler.rs"]
-mod tests;