**Apache Airflow version**: 2.1.0

**What happened**:
Airflow logging assume dict_key is type `str`
```
    logging.info("Dictionary where key is int type: %s", modified_table_mapping)
  File "/usr/lib64/python3.6/logging/__init__.py", line 1902, in info
    root.info(msg, *args, **kwargs)
  File "/usr/lib64/python3.6/logging/__init__.py", line 1308, in info
    self._log(INFO, msg, args, **kwargs)
  File "/usr/lib64/python3.6/logging/__init__.py", line 1444, in _log
    self.handle(record)
  File "/usr/lib64/python3.6/logging/__init__.py", line 1453, in handle
    if (not self.disabled) and self.filter(record):
  File "/usr/lib64/python3.6/logging/__init__.py", line 720, in filter
    result = f.filter(record)
  File "/bb/bin/airflow_env/lib/python3.6/site-packages/airflow/utils/log/secrets_masker.py", line 157, in filter
    record.__dict__[k] = self.redact(v)
  File "/bb/bin/airflow_env/lib/python3.6/site-packages/airflow/utils/log/secrets_masker.py", line 193, in redact
    return {dict_key: self.redact(subval, dict_key) for dict_key, subval in item.items()}
  File "/bb/bin/airflow_env/lib/python3.6/site-packages/airflow/utils/log/secrets_masker.py", line 193, in <dictcomp>
    return {dict_key: self.redact(subval, dict_key) for dict_key, subval in item.items()}
  File "/bb/bin/airflow_env/lib/python3.6/site-packages/airflow/utils/log/secrets_masker.py", line 189, in redact
    if name and should_hide_value_for_key(name):
  File "/bb/bin/airflow_env/lib/python3.6/site-packages/airflow/utils/log/secrets_masker.py", line 74, in should_hide_value_for_key
    name = name.strip().lower()
AttributeError: 'int' object has no attribute 'strip'
```

**How to reproduce it**:
Define a dictionary where the type of keys is `int` and print it in any Airflow tasks.

tests/utils/log/test_secrets_masker.py
filt = SecretsMasker()
        filt.add_mask(value, name)
        assert filt.patterns == expected_mask
    @pytest.mark.parametrize(
        ("patterns", "name", "value", "expected"),
        [
            ({"secret"}, None, "secret", "***"),
            (
                {"secret", "foo"},
                None,
                {"apikey": "secret", "other": {"val": "innocent", "password": "foo"}},
                {"apikey": "***", "other": {"val": "innocent", "password": "***"}},
            ),
            ({"secret", "other"}, None, ["secret", "other"], ["***", "***"]),
            
            ({"secret", "other"}, None, {"data": {"secret": "secret"}}, {"data": {"secret": "***"}}),
            (
                
                {"secret"},
                "api_key",
                {"other": "innoent", "nested": ["x", "y"]},
                {"other": "***", "nested": ["***", "***"]},
            ),
            (
                
                set(),