Added _ca_certs property to _SSLAdapter to properly support pickling (broke in SDK v11.33)

[dennissiemensma]

In Dropbox SDK v11.33 PR #385 added a new _ca_certs property to _SSLAdapter.

However, the property is dynamically specified, which breaks unpickling it using pickle.loads():

  AttributeError: '_SSLAdapter' object has no attribute '_ca_certs'

The fix is simple: Define the property instead of dynamically defining it.

Checklist

General Contributing

• [ ] Have you read the Code of Conduct ? -> Broken! ❌
• [x] Have you read signed the CLA?

Is This a Code Change?

• [ ] Non-code related change (markdown/git settings etc)
• [x] SDK Code Change
• [ ] Example/Test Code Change

Validation

• [x] Does tox pass?
• [ ] Do the tests pass?

[dennissiemensma]

The Code of Conduct seems broken guys, HTTP 403: https://opensource.dropbox.com/coc/

[dennissiemensma]

I pre-ran the tests on my fork, most succeed, but some integration tests are failing (on purpose?):

• https://github.com/dennissiemensma/dropbox-sdk-python/pull/1

  OAuth2 access token or refresh token or app key/secret must be set

[greg-db]

Thanks! I'll ask the team to review this (as well as check on that 403 on the COC).

[dennissiemensma]

Great, thanks!

[greg-db]

This is released in v11.34.0 now. Thanks again!