Update maintainer

Author: alanocallaghan

DESCRIPTION

@@ -1,12 +1,12 @@
 Package: scater
 Type: Package
 Authors@R: c(
-        person("Davis", "McCarthy", role=c("aut", "cre"), email="davis@ebi.ac.uk"),
+        person("Davis", "McCarthy", role=c("aut"), email="davis@ebi.ac.uk"),
         person("Kieran", "Campbell", role=c("aut"), email="kieran.campbell@sjc.ox.ac.uk"),
         person("Aaron", "Lun", role = c("aut", "ctb"), email="infinite.monkeys.with.keyboards@gmail.com"),
         person("Quin", "Wills", role=c("aut"), email="qilin@quinwills.net"),
         person("Vladimir", "Kiselev", role=c("ctb"), email="vk6@sanger.ac.uk"),
-        person("Alan", "O'Callaghan", role=c("ctb"), email="alan.ocallaghan@outlook.com"))
+        person("Alan", "O'Callaghan", role=c("ctb", "cre"), email="alan.ocallaghan@outlook.com"))
 Version: 1.17.5
 Date: 2020-09-06
 License: GPL-3