Don't force LF line endings on zsh script

> the pattern is not necessary, as the scripts with those extensions
> are not executable and are crunched into an OCaml script

ocaml#4242 (comment)

.gitattributes

@@ -3,7 +3,6 @@
 
 # Shell scripts, autoconf, etc. must have LF endings, even on Windows
 *.sh text eol=lf
-*.zsh text eol=lf
 configure text eol=lf -diff
 configure.ac text eol=lf
 msvs-detect text eol=lf