font-lock: remove "foreign export" highlight

"foreign export" isn't a thing in PureScript. It's a legacy from
haskell-mode, remove it.

Author: Hi-Angel

purescript-font-lock.el

@@ -230,13 +230,6 @@ Returns keywords suitable for `font-lock-keywords'."
              (2 (symbol-value 'purescript-keyword-face) nil lax))
 
             (,reservedsym 1 (symbol-value 'purescript-operator-face))
-            ;; Special case for `foreign export'
-            ;; keywords in foreign export statements but are not otherwise reserved.
-            ("\\<\\(foreign\\)[ \t]+\\(export\\)[ \t]+\\(?:\\(ccall\\|stdcall\\|cplusplus\\|jvm\\|dotnet\\)[ \t]+\\)?"
-             (1 (symbol-value 'purescript-keyword-face) nil lax)
-             (2 (symbol-value 'purescript-keyword-face) nil lax)
-             (3 (symbol-value 'purescript-keyword-face) nil lax))
-
             ;; Toplevel Declarations.
             ;; Place them *before* generic id-and-op highlighting.
             (,topdecl-var  (1 (symbol-value 'purescript-definition-face)))