patch 8.2.2788: Raku is now the only name what once was called perl6

Problem:    Raku is now the only name what once was called perl6.
Solution:   Adjust the filetype detection. (closes #8120)
diff --git a/src/version.c b/src/version.c
index 54bf127..1926724 100644
--- a/src/version.c
+++ b/src/version.c
@@ -751,6 +751,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    2788,
+/**/
     2787,
 /**/
     2786,