fix: upgrade to Sinatra 3 and use Rack::Session::Cookie in tests

[stevehobbsdev]

Changes

This fixes an issue with a test that verifies how the authorization params are written to the session (as a plain hash) that does not work using Sinatra 3. The default session store for 3 was changed Rack::Protection::EncryptedCookie, and this test does not take into account the cookie being encrypted.

This PR:

• Upgrades Sinatra to 3
• Uses the Sinatra 2 default cookie store of Rack::Session::Cookie for the purposes of tests

References

Fixes #162

Testing

This change was tested manually using the debian:sid Docker image.