Added Dehumanize support for Czech and Slovak Locales

[anishnya]

Pull Request Checklist

Adds Dehumanize support for Czech and Slovak locales and closes #1078.

• [x ] 🧪 Added tests for changed code.
• [ x] 🛠️ All tests pass when run locally (run tox or make test to find out!).
• [ x] 🧹 All linting checks pass when run locally (run tox -e lint or make lint to find out!).
• [ x] 📚 Updated documentation for changed code.
• [ x] ⏩ Code is up-to-date with the master branch.

If you have any questions about your code changes or any of the points above, please submit your questions along with the pull request and we will try our best to help!

Description of Changes

[codecov[bot]]

Codecov Report

Merging #1079 (1a3e53a) into master (a2ebb7e) will not change coverage. The diff coverage is n/a.

@@            Coverage Diff            @@
##            master     #1079   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           10        10           
  Lines         2237      2237           
  Branches       439       439           
=========================================
  Hits          2237      2237           

Impacted Files	Coverage Δ
arrow/constants.py	100.00% <ø> (ø)
arrow/locales.py	100.00% <ø> (ø)

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