Fix io.imread behavior with pathlib.Path inputs

[grlee77]

Description

closes #5545

The following logic for using tifffile fails if fname is a Path:

    if plugin is None and hasattr(fname, 'lower'):
        if fname.lower().endswith(('.tiff', '.tif')):
            plugin = 'tifffile'

Casting the Path to str before this if statement resolves the issue.

Checklist

• Docstrings for all functions
• Gallery example in ./doc/examples (new features only)
• Benchmark in ./benchmarks, if your changes aren't covered by an
  existing benchmark
• Unit tests
• Clean style in the spirit of PEP8

For reviewers

• Check that the PR title is short, concise, and will make sense 1 year
  later.
• Check that new functions are imported in corresponding __init__.py.
• Check that new features, API changes, and deprecations are mentioned in
  doc/release/release_dev.rst.

[pep8speaks]

Hello @grlee77! Thanks for updating this PR. We checked the lines you've touched for PEP 8 issues, and found:

There are currently no PEP 8 issues detected in this Pull Request. Cheers! 🍻

Comment last updated at 2021-08-27 20:40:36 UTC

[soupault]

Thank you @grlee77 !
Based on the adoption of Path among the ecosystem, it still seems early to switch from str.