[weather] Fix OpenWeather API key failure by removing FORECAST

[ptrooms]

Yahoo stopped the functionality for openHAB, we switched to OpenWeather which generated an other issue. Why:

• OpenWeather discontinued the 5-day FORECAST included in their Free Plan which now generate an API-key error message in the openhab.log as the Weather bundle, unconditionally calls for FORECAST in succession to the default (actual) Weatherstatus.

For OpenWeather information reasons, pulling FORECAST from FreePlan, read thread 17136552

This change addresses the need by:

• return null in the FORECAST @override call

Fixes #5837

[ptrooms]

Please help/assist

Hi, I'm a bit lost and overwhelmed in the system of all GIT procedures to follow...... my "git"-branch is now updated on file READ.md and code-wise I've improved my solution-proposal that allows FORECAST for OpenWeatherMAP, if one specify "apikey2" in the weather.cfg. This will solve by default the API key failure and continu to allow for FORECAST queries in case persons have a paid plan (and then thus would have to specify apikey2).

What's the next step to do, if any ? ....... I've update my sources, push them to my remote-fork in branch 5837 ....... now what ? Let me know if I've missed something.

TIA Peter