Switch to gktsourceviewmm-4.0

Hello!

Archlinux switched to 4.0 because 3.0 is not maintained. Therefore the package isn't buildable anymore:

/home/peter/downloads/jucipp-git/src/jucipp/src/source_base.hpp:7:10: fatal error: gtksourceviewmm.h: No such file or directory
    7 | #include <gtksourceviewmm.h>
      |          ^~~~~~~~~~~~~~~~~~~
compilation terminated.
make[2]: *** [src/CMakeFiles/juci_shared.dir/build.make:79: src/CMakeFiles/juci_shared.dir/autocomplete.cpp.o] Error 1
make[1]: *** [CMakeFiles/Makefile2:237: src/CMakeFiles/juci_shared.dir/all] Error 2
make: *** [Makefile:156: all] Error 2
==> ERROR: A failure occurred in package_jucipp-git().
    Aborting...

Can we switch to 4.0?
Thank you