fixed #3 and CRAN check: corrected and updated citation

inst/CITATION

-citHeader("To cite the 'SISIR' package in publications, use:")
-
-year = sub('.*(2[[:digit:]]{3})-.*', '\\1', meta$Date, perl = TRUE)
-vers = paste('R package version', meta$Version)
-
-citEntry(
-  entry = 'manual',
-  title = paste('SISIR:', meta$Title),
-  author = as.person(meta$Author),
-  year = year,
-  note = vers,
-  textVersion = paste('Villa-Vialaneix N., Picheny V., Servien R. (', year, ') SISIR: ', meta$Title, '. ', vers, '.', sep = '')
+bibentry(
+  bibtype = "Article",
+  textVersion = "Picheny V., Servien R., Villa-Vialaneix N. (2019) Interpretable sparse sliced inverse regression for functional data. Statistics and Computing, 29(2), 255-267.",
+  header = "To cite SISIR in publications, please use",
+  author = "Victor Picheny, Rémi Servien, Nathalie Villa-Vialaneix",
+  title = "Interpretable sparse sliced inverse regression for functional data",
+  journal = "Statistics and Computing",
+  year = "2019",
+  volume = "29",
+  issue = "2", 
+  pages = "255-267"
 )
 
-citEntry(
-  entry = 'unpublished',
-  title = 'Interpretable sparse SIR for digitized functional data',
-  author = personList(as.person("Victor Picheny"), as.person("R\'emi Servien"), as.person("Nathalie Villa-Vialaneix")),
-  note = 'Preprint',
-  
-  textVersion = paste('Picheny V., Servien R., Villa-Vialaneix N. (2016)',
-                      'Interpretable sparse SIR for digitized functional data.',
-                      'Preprint.')
-)
\ No newline at end of file
+bibentry(
+  bibtype = "Unpublished",
+  textVersion = "Servien R., Vialaneix N. (2023) A random forest approach for interval selection in functional regression. Preprint",
+  author = "Rémi Servien, Nathalie Vialaneix",
+  title = "A random forest approach for interval selection in functional regression",
+  note = "Preprint",
+  year = "2023"
+)