votca-*: add v1.6.3

[junghans]

No description provided.

[junghans]

Huh?

$ spack install -v votca-xtp@1.6.3 ^votca-tools+mkl
==> Error: Multiple providers found for 'fftw-api@3': ['fftw@3.3.8%gcc@8.2.0+mpi~openmp~pfft_patches precision=double,float arch=linux-centos7-haswell', 'intel-parallel-studio@professional.2020.2%gcc@8.2.0~advisor~clck+daal~gdb~ilp64~inspector+ipp~itac+mkl+mpi~newdtags+rpath+shared+tbb~vtune auto_dispatch=none threads=none arch=linux-centos7-haswell']

how do I fix that?

[adamjstewart]

Multiple providers found for virtual dependency (#4107, #7339, #7901, #8059, #8133, #9753, #11987, #13821)

Common error, still not sure if we've figured out why. Hopefully fixed by new concretizer

[junghans]

@adamjstewart thanks. spack install votca-xtp (without mkl) works, so please review.