Fix TLS 1.3 client tests with requests

[webknjaz]

❓ What kind of change does this PR introduce?

• 🐞 bug fix
• 🐣 feature
• 📋 docs update
• 📋 tests/coverage improvement
• 📋 refactoring
• 💥 other

📋 What is the related issue number (starting with #)

Closes #173

❓ What is the current behavior? (You can also link to an open issue here)

OpenSSL.SSL.Error happens.

❓ What is the new behavior (if this is a feature change)?

No OpenSSL.SSL.Error.

📋 Other information:

Ref https://github.com/kennethreitz/requests/issues/4961
Ref urllib3/urllib3#1496

📋 Checklist:

• I think the code is well written
• I wrote good commit messages
• I have squashed related commits together after the changes have been approved
• Unit tests for the changes exist
• Integration tests for the changes exist (if applicable)
• I used the same coding conventions as the rest of the project
• The new code doesn't generate linter offenses
• Documentation reflects the changes
• The PR relates to only one subject with a clear title
  and description in grammatically correct, complete sentences

---

This change is