fixed f string formatting

stickler doesn't like it but it doesn't work with spaces

Author: bgpierc

pvlib/iotools/pvgis.py

@@ -681,7 +681,7 @@ def get_pvgis_horizon(latitude, longitude, proxies=None, url=URL):
         Pandas dataframe of the retrived horizon
     '''
     res = requests.get(url +
-                       f'printhorizon?lat={ latitude }&lon={ longitude }',
+                       f'printhorizon?lat={latitude}&lon={longitude}',
                        proxies=proxies, verify=False)
     res.raise_for_status()
     string = str(io.BytesIO(res.content).read().decode('UTF-8'))