Bug: test_categories.py fails 4 tests

[Gonzom]

test_categories.py fails 4 tests with the following errors when run by itself.

Steps to reproduce:

1. pytest tests\test_categories.py

Result:

FAILED tests/test_categories.py::TestCategories::test_creating_new_category - assert False
FAILED tests/test_categories.py::TestCategories::test_get_user_categories - AssertionError: assert {('color', '1...'user_id', 1)} == {('color', '1...'user_id', 1)}
FAILED tests/test_categories.py::TestCategories::test_get_category_by_name - AssertionError: assert {('color', '1...'user_id', 1)} == {('color', '1...'user_id', 1)}
FAILED tests/test_categories.py::TestCategories::test_get_category_by_color - AssertionError: assert {('color', '1...'user_id', 1)} == {('color', '1...'user_id', 1)}