Update citation

Author: hadley

inst/CITATION

@@ -1,18 +1,10 @@
-citHeader("To cite the testthat package in publications, use:")
-
-citEntry(
-  entry = "Article",
-  author = personList(as.person("Hadley Wickham")),
+bibentry(
+  "Article",
+  author = "Hadley Wickham",
   title = "testthat: Get Started with Testing",
   journal = "The R Journal",
   year = 2011,
   volume = 3,
   pages = "5--10",
-  url = "https://journal.r-project.org/archive/2011-1/RJournal_2011-1_Wickham.pdf",
-  textVersion = paste(
-    "Hadley Wickham. testthat: Get Started with Testing.",
-    "The R Journal, vol. 3, no. 1, pp. 5--10, 2011"
-  )
+  url = "https://journal.r-project.org/archive/2011-1/RJournal_2011-1_Wickham.pdf"
 )
-
-citFooter("As testthat is continually evolving, you may want to cite its version number. Find it with 'help(package=testthat)'.")