Update CITATION

Fixing the wrong URL, re: PR #503

Author: Taylor Arnold

R-packages/covidcast/inst/CITATION

@@ -16,7 +16,7 @@ bibentry(bibtype = "Manual",
                     person(given = "Ryan", family = "Tibshirani")),
          year = year,
          note = note,
-         url = " https://cmu-delphi.github.io/covidcast/covidcastR/")
+         url = "https://cmu-delphi.github.io/covidcast/covidcastR/")
 
 citFooter(paste0(
   c("For information about citing the datasets provided by the API, see: ",