Fix flake8 do not compare types error

[msabramo]

• Please check if the PR fulfills these requirements

• Tests for the changes have been added

• Docs have been added / updated

• All CI checks are green

• What kind of change does this PR introduce?
  Build fix

• What is the current behavior?
  Running tox -e py39 or pre-commit run --all-files leads to a flake8 failure:

  detect_secrets/plugins/ibm_cloud_iam.py:37:8: E721 do not compare types, for exact checks use `is` / `is not`, for 
  instance checks use `isinstance()`
  

• What is the new behavior (if this is a feature change)?
  flake8 passes. For example:

  (.venv)
  abramowi at Marcs-MacBook-Pro-3 in ~/Code/OpenSource/detect-secrets (fix-flake8-do-not-compare-types-error●)
  $ pre-commit run --all-files
  Check builtin type constructor use.......................................Passed
  Check docstring is first.................................................Passed
  Debug Statements (Python)................................................Passed
  Fix double quoted strings................................................Passed
  Fix End of Files.........................................................Passed
  Tests should end in _test.py.............................................Passed
  Flake8...................................................................Passed
  Trim Trailing Whitespace.................................................Passed
  Reorder python imports...................................................Passed
  Add trailing commas......................................................Passed
  autopep8.................................................................Passed
  Detect secrets...........................................................Passed
  

• Does this PR introduce a breaking change?
  No

• Other information:

[lorenzodb1]

Addressed in #724