Update license headers.

engine-api.py

engine-core.py

guru.py

modules/base/config.py

modules/base/enum.py

modules/base/exceptions.py

modules/base/logger.py

modules/base/utils.py

modules/cli_tool/padavan.py

modules/communication/liquidsoap/client.py

modules/communication/liquidsoap/playerclient.py

modules/communication/mail.py

modules/communication/redis/adapter.py

modules/communication/redis/messenger.py

modules/communication/redis/statestore.py

modules/core/engine.py

modules/core/monitor.py

modules/core/startup.py

modules/core/state.py

modules/database/model.py