test: update system test fixtures to create necessary tables

[tswast]

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Fixes #94 🦕

[tswast]

Note: I still expect the tests to fail due to the docs session failing: #90

[tswast]

As expected:

nox > Ran multiple sessions:
nox > * unit-3.6: success
nox > * unit-3.7: success
nox > * unit-3.8: success
nox > * unit-3.9: success
nox > * system-3.8: success
nox > * cover: success
nox > * lint: success
nox > * lint_setup_py: success
nox > * blacken: success
nox > * docs: failed