fix(sensor): removes resolution from fetch one response to only retur…

[GustaafL]

Description

In PR #767 the fetch one sensor incorrectly returned resolution in the API response. This field would have the same value as event_resolution. The fetch one sensor endpoint now only returns the event_resolution

Look & Feel

Before:
{
"name": "some gas sensor",
"unit": "m³/h",
"entity_address": "ea1.2023-08.localhost:fm1.1",
"event_resolution": "PT10M",
"resolution": "PT10M",
"generic_asset_id": 4,
"timezone": "UTC",
}
After:

        {
            "name": "some gas sensor",
            "unit": "m³/h",
            "entity_address": "ea1.2023-08.localhost:fm1.1",
            "event_resolution": "PT10M",
            "generic_asset_id": 4,
            "timezone": "UTC",
        }

• I agree to contribute to the project under Apache 2 License.
• To the best of my knowledge, the proposed patch is not based on code under GPL or other license that is incompatible with FlexMeasures

[nhoening]

Thanks, good catch!