Use non-deprecated resampling constants

[alessiamarcolini]

Description

Use new resampling constants after upgrading to Pillow 9.1.0
https://pillow.readthedocs.io/en/stable/releasenotes/9.1.0.html#constants

Types of Changes

• Core
• Bugfix
• New feature
• Enhancement/optimization
• Documentation

Issues Fixed or Closed by This PR

• Fixes:

Checklist

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• I have tested the changes and verified that they work and don't break anything (as well as I can manage).

[codecov]

Codecov Report

Merging #408 (c378784) into master (7179672) will not change coverage.
The diff coverage is 100.00%.

@@            Coverage Diff            @@
##            master      #408   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           17        17           
  Lines         1433      1433           
  Branches       223       223           
=========================================
  Hits          1433      1433           

Impacted Files	Coverage Δ
histolab/slide.py	100.00% <100.00%> (ø)

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 7179672...c378784. Read the comment docs.