lang/lfortran: upgrade to v0.30.0

Release notes at https://github.com/lfortran/lfortran/releases/tag/v0.30.0.

Remark: lfortran only supports obsolete versions of Xeus (to get a kernel
for Jupyter), therefore it has been disabled.

(cherry picked from commit 9ee01024f2b292c752b1e0d1dc98c810f27133ce)