Fix dev dependencies

[agardnerIT]

1. Install dev dependencies

pip install pip-tools
pip-compile requirements-dev.in
pip install -r requirements-dev.in

2. Observed output

ERROR: pip's dependency resolver does not currently take into account all the packages that are installed. This behaviour is the source of the following dependency conflicts.
jsonschema 4.19.0 requires attrs>=22.2.0, but you have attrs 21.4.0 which is incompatible.
referencing 0.30.2 requires attrs>=22.2.0, but you have attrs 21.4.0 which is incompatible.

3. requirements-dev.txt

attrs==21.4.0
    # via pytest

[agardnerIT]

Solution. Add attrs==23.1.0 to top of requirements-dev.in