kde-kdoctools: change qt to qt@5

Formula/kde-kdoctools.rb

@@ -9,6 +9,7 @@ class KdeKdoctools < Formula
     "LGPL-2.1-or-later",
     any_of: ["LGPL-2.1-only", "LGPL-3.0-only"],
   ]
+  revision 1
   head "https://invent.kde.org/frameworks/kdoctools.git"
 
   bottle do
@@ -95,7 +96,7 @@ class KdeKdoctools < Formula
     cp_r (pkgshare/"tests"), testpath
 
     args = std_cmake_args
-    args << "-DQt5_DIR=#{Formula["qt"].opt_prefix/"lib/cmake/Qt5"}"
+    args << "-DQt5_DIR=#{Formula["qt@5"].opt_prefix/"lib/cmake/Qt5"}"
 
     system "cmake", testpath.to_s, *args
     system "make"