density.h not available

[Alessandro-Barbieri]

muster upstream is now https://github.com/LLNL/muster and master doesn't have density.h

libtool: compile:  x86_64-pc-linux-gnu-g++ -DHAVE_CONFIG_H -I. -I../.. -DCLUSTERING_SUITE -I/var/tmp/portage/sys-cluster/clusteringsuite-2.6.9-r3/work/clustering-suite-2.6.9/include -I/var/tmp/portage/sys-cluster/clusteringsuite-2.6.9-r3/work/clustering-suite-2.6.9/src/BasicClasses -I/var/tmp/portage/sys-cluster/clusteringsuite-2.6.9-r3/work/clustering-suite-2.6.9/common_utilities -I/usr/include/libxml2 -I/usr/include -I/usr/include -I/usr/include -I/usr/include -I/usr/include/ANN -Os -pipe -march=native -D_FILE_OFFSET_BITS=64 -D_LARGEFILE64_SOURCE -c OPTICS.cpp  -fPIC -DPIC -o .libs/libClustering_la-OPTICS.o                                                                                            
MUSTER_DBSCAN.cpp:42:10: fatal error: density.h: No such file or directory                                            
   42 | #include <density.h>                                                                                          
      |          ^~~~~~~~~~~                                                                                          
compilation terminated.