Time pattern syntax improvements

[DillonJ]

When importing some time pattern data using spinedb_api.import_data() the following syntax generates an error:

{"type": "time_pattern", "data": {"M1-7": 1, "M8": 0, "M9-12": 1}}

I have to instead write:

{"type": "time_pattern", "data": {"M1-7": 1, "M8-8": 0, "M9-12": 1}}

It feels like the first syntax should also work