snippets: fix template prefix for non-symbol chars

Fixes inserting "#include" template after "#" which is a non-symbol char.
2 jobs for master in 58 minutes and 52 seconds (queued for 1 second)
Status Job ID Name Coverage
  Test
passed flatpak #1208160
flatpak

00:51:58

 
  Deploy
passed nightly #1208161

00:06:54