THANKS.in: Add new authors

Add the new Git commit authors to the THANKS.in file.

THANKS.in

@@ -308,3 +308,14 @@ Luca Corti
 Jethro Carr
 Evgeni Golov
 Oskar Liljeblad
+Andrew Widdersheim
+Anton Lofgren
+Damian Myerscough
+Davide Madrisan
+Gunnar Beutner
+Joseph Gooch
+Lars Vogdt
+Ricardo Maraschini
+Spenser Reinhardt
+Stephane Lapie
+Tilmann Bubeck