fix bibtex comma

Author: NathanielF

examples/references.bib

@@ -457,7 +457,7 @@ @book{kline2023principles
 	year          = 2023,
 	publisher     = {Guilford Publications},
 	series        = {Methodology in the Social Sciences Series},
-	url           = {https://books.google.ie/books?id=t2CvEAAAQBAJ},
+	url           = {https://books.google.ie/books?id=t2CvEAAAQBAJ}
 }
 @article{koren2009matrixfactorization,
   author        = {Koren, Yehuda and Bell, Robert and Volinsky, Chris},
@@ -880,7 +880,7 @@ @book{vehkalahti2019multivariate
 	year          = {2019},
 	publisher     = {CRC Press, Taylor \& Francis Group},
 	series        = {A Chapman \& Hall book},
-	url           = {https://books.google.ie/books?id=LX97uwEACAAJ},
+	url           = {https://books.google.ie/books?id=LX97uwEACAAJ}
 }
 @online{vehtari2022Birthdays,
   title         = {Bayesian workflow book - Birthdays},