Remove patch, let's see if we no longer need it

debian/patches/series

@@ -1 +0,0 @@
-set-qt-plugins-dir-via-configure.patch

debian/patches/set-qt-plugins-dir-via-configure.patch

@@ -1,17 +0,0 @@
---- a/src/CMakeLists.txt
-+++ b/src/CMakeLists.txt
-@@ -51,10 +51,10 @@
- endif()
- 
- # execute the command "qmake -query QT_INSTALL_PLUGINS" to get the path of plugins dir.
--execute_process(COMMAND ${QT_QMAKE_EXECUTABLE} -query QT_INSTALL_PLUGINS
--    OUTPUT_VARIABLE QT_PLUGINS_DIR
--    OUTPUT_STRIP_TRAILING_WHITESPACE
--)
-+#execute_process(COMMAND ${QT_QMAKE_EXECUTABLE} -query QT_INSTALL_PLUGINS
-+#    OUTPUT_VARIABLE QT_PLUGINS_DIR
-+#    OUTPUT_STRIP_TRAILING_WHITESPACE
-+#)
- if(QT_PLUGINS_DIR)
-     message(STATUS "Qt6 plugin directory:" "${QT_PLUGINS_DIR}")
- else()