vim-patch:9.0.0562: HSL playlist files are not recognized (#20307)

Problem:    HSL playlist files are not recognized.
Solution:   Add a pattern to recognize HSL palylist files. (Benoît Ryder,
            closes vim/vim#11204)
35fdd9a67d

runtime/lua/vim/filetype.lua

@@ -473,6 +473,7 @@ local extension = {
   hex = 'hex',
   ['h32'] = 'hex',
   hjson = 'hjson',
+  m3u8 = 'hlsplaylist',
   hog = 'hog',
   hws = 'hollywood',
   hoon = 'hoon',