Change `PHOTOVOLTAIC` to `PV`#376

tiyash-basu-frequenz merged 1 commit intofrequenz-floss:v0.x.xfrequenz-floss/frequenz-api-common:v0.x.xfrom

tiyash-basu-frequenz:pvtiyash-basu-frequenz/frequenz-api-common:pvCopy head branch name to clipboard