The forecast attribute was removed from the state object of weather entities about 18 month ago, there is no way to access it directly with a state template. You will need to follow the example in the docs showing how to create a template sensor using the action weather.get_forecasts.
I thought you had asked for the maximum forecasted temperature. Your modified version, of my example’s template, does not do that.
EDIT:
I see you changed the value of type from hourly to daily.
Very odd indeed because the example I offered does work.
BTW, the reason my template excludes strings (using reject('string')) is because there are rare occasions when met.no doesn’t report a numeric value for temperature.