Fix linting issues

b_asic/codegen/vhdl/__init__.py

b_asic/codegen/vhdl/architecture.py

b_asic/codegen/vhdl/common.py

b_asic/codegen/vhdl/entity.py

b_asic/gui_utils/about_window.py

b_asic/gui_utils/plot_window.py

b_asic/operation.py

b_asic/research/__init__.py

b_asic/resources.py

b_asic/simulation.py

test/fixtures/operation_tree.py

test/fixtures/schedule.py

test/test_process.py

test/test_resources.py

test/test_sfg.py

test/test_signal_generator.py