Revert local sh.vim downgrade change as bug was fixed in upstream

See #1358 which performed the
downgrade and rationale.

This should also fix build breaking in CI.

runtime/syntax/sh.vim

@@ -190,8 +190,10 @@ syn region shEmbeddedEcho contained matchgroup=shStatement start="\<print\>" ski
 " =====
 if exists("b:is_kornshell") || exists("b:is_bash") || exists("b:is_posix")
  syn match shStatement "\<alias\>"
- syn region shAlias matchgroup=shStatement start="\<alias\>\s\+\(\h[-._[:alnum:]]\+\)\@="  skip="\\$" end="\>\|`"
- syn region shAlias matchgroup=shStatement start="\<alias\>\s\+\(\h[-._[:alnum:]]\+=\)\@=" skip="\\$" end="="
+ syn region shAlias matchgroup=shStatement start="\<alias\>\s\+\(\h[-._[:alnum:]]*\)\@="  skip="\\$" end="\>\|`"
+ syn region shAlias matchgroup=shStatement start="\<alias\>\s\+\(\h[-._[:alnum:]]*=\)\@=" skip="\\$" end="="
+" syn region shAlias matchgroup=shStatement start="\<alias\>\s\+\(\h[-._[:alnum:]]\+\)\@="  skip="\\$" end="\>\|`"
+" syn region shAlias matchgroup=shStatement start="\<alias\>\s\+\(\h[-._[:alnum:]]\+=\)\@=" skip="\\$" end="="
 
  " Touch: {{{1
  " =====
@@ -483,7 +485,9 @@ endif
 
 " Parameter Dereferencing: {{{1
 " ========================
-if !exists("g:sh_no_error") && !(exists("b:is_bash") || exists("b:is_kornshell") || exists("b:is_posix"))
+" Note: sh04 failure with following line
+"if !exists("g:sh_no_error") && !(exists("b:is_bash") || exists("b:is_kornshell") || exists("b:is_posix"))
+if !exists("g:sh_no_error")
  syn match  shDerefWordError	"[^}$[~]"	contained
 endif
 syn match  shDerefSimple	"\$\%(\h\w*\|\d\)"	nextgroup=@shNoZSList