Actualize flags

[hypnoglow]

Fix flags according to documentation.

1. I haven't found anything about MetNoLicense.
2. DarkSkyUnavailable is actually not a bool, but a string.

   "flags": {
     "darksky-unavailable": "Dark Sky covers the given location, but all stations are currently unavailable.",
     "sources": [
       "isd",
       "cmc",
       "gfs",
       "hrrr",
       "madis",
       "nam",
       "sref",
       "darksky"
     ],
     "units": "us"
    },
   

And the whole request fails because of conversion failure: json: cannot unmarshal string into Go struct field Flags.darksky-unavailable of type bool.

[coveralls]

Coverage remained the same at 94.34% when pulling f0380f9 on hypnoglow:fix-flags into 3ad8c10 on adlio:master.

[coveralls]

Coverage remained the same at 94.34% when pulling f0380f9 on hypnoglow:fix-flags into 3ad8c10 on adlio:master.

[adlio]

Thank you for your contribution!