Enforce string-formatting with f-strings (#10980)

* First third

* Styling and fix mistake

* Quality

* All the rest

* Treat %s and %d

* typo

* Missing )

* Apply suggestions from code review

Co-authored-by: Lysandre Debut <lysandre@huggingface.co>

Co-authored-by: Lysandre Debut <lysandre@huggingface.co>

tests/test_modeling_tf_mbart.py

@@ -291,10 +291,9 @@ def _assert_tensors_equal(a, b, atol=1e-12, prefix=""):
             return True
         raise
     except Exception:
-        msg = "{} != {}".format(a, b)
-        if prefix:
-            msg = prefix + ": " + msg
-        raise AssertionError(msg)
+        if len(prefix) > 0:
+            prefix = f"{prefix}: "
+        raise AssertionError(f"{prefix}{a} != {b}")
 
 
 def _long_tensor(tok_lst):