Apply Rust formatting standards

- Reformat long format statement to multi-line style
- Follows cargo fmt conventions for code consistency

Author: Oblivionsage

src/rust/src/backend/ciphers.rs

@@ -508,7 +508,10 @@ impl PyAEADDecryptionContext {
             return Err(CryptographyError::from(
                 pyo3::exceptions::PyValueError::new_err(
                     // Defensive error handling - rarely triggered in normal usage
-                    format!("Authentication tag cannot be more than {} bytes.", GCM_STANDARD_TAG_SIZE),
+                    format!(
+                        "Authentication tag cannot be more than {} bytes.",
+                        GCM_STANDARD_TAG_SIZE
+                    ),
                 ),
             ));
         }