poppler: remove unused pcre

Poppler does not directly depend on PCRE.

It was added in <https://github.com/NixOS/nixpkgs/pull/127832>,
presumably to suppress CMake complaining about `glib-2.0` needing `pcre`
because CMake is not aware that we interpret `Requires.private`
field in pkg-config files differently.
And GLib since switched to pcre2 anyway so the warning is back.

pkgs/development/libraries/poppler/default.nix

···
 , fetchFromGitLab
 , cairo
 , cmake
-, pcre
 , boost
 , cups-filters
 , curl
···
 
   buildInputs = [
     boost
-    pcre
     libiconv
     libintl
   ] ++ lib.optionals withData [