Always put connection back into pull

[minyoung]

What is the current behavior?

Connections are not put back into the pool if there is an exception Related issue https://github.com/malthe/pq/issues/41

What is the new behavior?

Connections now returned to the pool if there is an exception

Checklist

Please make sure the following requirements are complete:

• [x] Tests for the changes have been added (for bug fixes / features)
• [x] Docs have been reviewed and added / updated if needed (for bug fixes / features)
• [ ] All automated checks pass (CI/CD)

[minyoung]

The CI check seems to be failing because of:

  error: invalid command 'bdist_wheel'
  ----------------------------------------
  ERROR: Failed building wheel for psycopg2cffi
ERROR: Failed to build one or more wheels

Which seems unrelated to my code change?

[malthe]

I need to figure out why the Github action fails on this. It should be unrelated to this pull request.

Nice contribution!