Update src/cargo/util/toml/embedded.rs

Co-authored-by: Scott Schafer <[email protected]>

src/cargo/util/toml/embedded.rs

@@ -239,7 +239,7 @@ fn split_source(input: &str) -> CargoResult<Source<'_>> {
                 // Attribute
                 return Ok(source);
             }
-            anyhow::bail!("found {tick_end} backticks in rust frontmatter, expected at least 3")
+            anyhow::bail!("found {tick_end} `{tick_char}` in rust frontmatter, expected at least 3")
         }
         _ => source.content.split_at(tick_end),
     };