bump VERSION to 3.8-rc.2 #5553

Job	Run time
clang-format	17s
black	30s
copyright_headers	20s
cppcheck	8m 13s
flake8	25s
forbidden_types	14s
isort	11s
lychee_IGNORED	22s
mypy	35s
pydocstyle	25s
pylint	40s
rstcheck	20s
unused_names	17s
vale	34s
sphinx-rtd	3m 14s
sphinx-conda	0s
build_macos (macos-latest, clang, openmp, mpi, python, gsl, ltdl, boost, hdf5, optimize, warning)	12m 6s
build_linux (ubuntu-22.04, gcc, boost, optimize, warning)	12m 45s
build_linux (ubuntu-22.04, gcc, openmp, python, gsl, ltdl, boost, optimize, warning)	18m 7s
build_linux (ubuntu-22.04, gcc, mpi, python, gsl, ltdl, boost, optimize, warning)	18m 29s
build_linux (ubuntu-22.04, gcc, openmp, mpi, python, gsl, ltdl, boost, hdf5, sionlib, libneurosim...	30m 57s
	1h 49m 1s

Provide feedback