deskutils/lumina-pdf: fix build on GCC architectures

Add include memory to drawablepage.h:
In file included from Renderer-poppler.cpp:2:
drawablepage.h:34:8: error: 'unique_ptr' in namespace 'std' does not name a template type

34 |   std::unique_ptr<Poppler::Page> page;
   |        ^~~~~~~~~~

drawablepage.h:7:1: note: 'std::unique_ptr' is defined in header '<memory>'; did you forget to '#include <memory>'?

  6 | #include <poppler/qt5/poppler-qt5.h>
+++ |+#include <memory>
  7 |

PR: 241002
Approved by: ken@ixsystems.com (maintainer timeout), linimon (mentor)