Mypy Errors with new version of mypy

[gucifer]

🐛 Bug description

With the new version of mypy, ignite/handlers/checkpoint.py and ignite/utils.py has some errors related to typing.

ignite/utils.py:161: error: unused "type: ignore" comment
        existing = name is None or name in logging.root.manager.loggerDict...
        ^
ignite/handlers/checkpoint.py:9: error: unused "type: ignore" comment
    from tempfile import _TemporaryFileWrapper  # type: ignore[attr-define...
    ^
ignite/handlers/checkpoint.py:695: error: Incompatible types in assignment
(expression has type "None", variable has type "_TemporaryFileWrapper") 
[assignment]
                tmp = None  # type: _TemporaryFileWrapper
                      ^
ignite/handlers/checkpoint.py:697: error: Incompatible types in assignment
(expression has type "IO[bytes]", variable has type "_TemporaryFileWrapper") 
[assignment]
                    tmp = tempfile.NamedTemporaryFile(delete=False, dir=se...
                          ^
Found 4 errors in 2 files (checked 98 source files)

Environment

• Ignite Version (e.g., 0.3.0): Current master branch
• OS (e.g., Linux): Linux
• How you installed Ignite (conda, pip, source): source
• Python version: 3.8.6
• Any other relevant information:
  mypy version: mypy-0.901-cp38-cp38-manylinux2010_x86_64

[gucifer]

cc: @trsvchn and @ydcjeff

[sahilg06]

Hi @gucifer, I am new to PyTorch Ignite, I would like to have a go at this issue.