looks like we can't turn off DCMTK build

* there are still places in the code like

In file included from /home/runner/src/cmtk/core/libs/IO/cmtkImageFileDICOM.cxx:33:
/home/runner/src/cmtk/core/libs/IO/cmtkImageFileDICOM.h:45:10: fatal error: dcmtk/dcmdata/dctk.h: No such file or directory
   45 | #include <dcmtk/dcmdata/dctk.h>
      |          ^~~~~~~~~~~~~~~~~~~~~~

where headers are expected

build-cmtk.sh

@@ -4,7 +4,7 @@ set -e
 if [ ! -d "$HOME/usr/local/bin" ]; then
   mkdir -p $HOME/src && cd $HOME/src
   git clone --depth 50 https://github.com/jefferis/cmtk
-  cd cmtk/core && mkdir build && cd build && cmake -DCMTK_USE_DCMTK=OFF .. && make DESTDIR=$HOME/ all install
+  cd cmtk/core && mkdir build && cd build && cmake .. && make DESTDIR=$HOME/ all install
 else
   echo 'Using cached $HOME/usr/local directory.';
-fi
+fi