Force usage of webkit2gtk-4.1.

Index: CMakeLists.txt
--- CMakeLists.txt.orig
+++ CMakeLists.txt
@@ -247,10 +247,7 @@ if (WITH_GNUCASH)
     pkg_check_modules (WEBKIT REQUIRED IMPORTED_TARGET webkitgtk-3.0)
     set(WEBKIT1 1 CACHE INTERNAL "WebKitGtk")
   else()
-    pkg_check_modules (WEBKIT IMPORTED_TARGET webkit2gtk-4.0>=2.14.0)
-    if (NOT WEBKIT_FOUND)
-      pkg_check_modules (WEBKIT REQUIRED IMPORTED_TARGET webkit2gtk-4.1)
-    endif()
+    pkg_check_modules (WEBKIT REQUIRED IMPORTED_TARGET webkit2gtk-4.1)
     set(WEBKIT2 1 CACHE INTERNAL "WebKit2Gtk4")
   endif()
 
