For issue caosdb-server#110 (was caosdb-mysqlbackend#24).

Warning: may cause an infinite loop with output in one server thread on failure.

This reverts commit 63c8db1f.

Warning: may cause an infinite loop with output in one server thread.

Warning: may cause an infinite loop with output in one server thread.

# Summary

Adds a test for checking queries with quoted datetimes. See [#39](https://gitlab.com/caosdb/caosdb-server/-/issues/39) in caosdb-server.

# Focus

`test_issue_39` in `tests/test_issues_server.py`