Lint examples as part of CI

[KitBurgess]

Closes #65

[KitBurgess]

It worked!

#!/bin/bash -eo pipefail
. .venv/bin/activate
mypy docs/examples
docs/examples/0_sample_load_cargo_movements.py:21: error: Missing positional argument "filter_activity" in call to "search" of "CargoMovements"
Found 1 error in 1 file (checked 7 source files)

Exited with code exit status 1

[paddyroddy]

looks good

I personally like using pre-commit hooks which means that you can only push good commits to a repo https://github.com/VorTECHsa/mapping-service/tree/issue-194 i.e. look at the files .flake8, .isort.cfg, .pre-commit-config.yaml & pyproject.toml