fix buggy OPAM remove command

Author: palmskog

opam

@@ -10,7 +10,7 @@ license: "Proprietary"
 
 build: [ [ "./configure" ] [ make "-j%{jobs}%" ] ]
 install: [ make "install" ]
-remove: [ "sh" "-c" "rm -rf '%{lib}%/coq/user-contrib/InfSeqExt" ]
+remove: [ "sh" "-c" "rm -rf '%{lib}%/coq/user-contrib/InfSeqExt'" ]
 depends: [ "coq" {((>= "8.5" & < "8.6~") | (>= "8.6" & < "8.7~"))} ]
 
 tags: [ "keyword:temporal logic" "keyword:infinite transition systems" "keyword:coinduction" "category:Mathematics/Logic/Modal logic" ]