bump nbconvert extension in recent IPython easyconfigs to version 6.4.0

[casparvl]

Bump of nbconvert to version 6.4.0. The previous version of nbconvert that was in IPython-7.25.0-GCCcore-10.3.0.eb (nbconvert 6.1.0), could cause permission denied errors when run in a shared environment. See jupyter/nbconvert#1430 . This was fixed in PR jupyter/nbconvert#1646 . Since many EasyBuild users work in shared environments, I think this is a relevant fix to have included.

(created using eb --new-pr)

[boegel]

@boegelbot please test @ generoso

[boegelbot]

@boegel: Request for testing this PR well received on login1

PR test command 'EB_PR=14738 EB_ARGS= /opt/software/slurm/bin/sbatch --job-name test_PR_14738 --ntasks=4 ~/boegelbot/eb_from_pr_upload_generoso.sh' executed!

• exit code: 0
• output:

Submitted batch job 7898

Test results coming soon (I hope)...

- notification for comment with ID 1015817237 processed

Message to humans: this is just bookkeeping information for me,
it is of no use to you (unless you think I have a bug, which I don't).

[boegel]

lgtm

[boegel]

Test report by @boegel
SUCCESS
Build succeeded for 2 out of 2 (2 easyconfigs in total)
node3114.skitty.os - Linux centos linux 7.9.2009, x86_64, Intel(R) Xeon(R) Gold 6140 CPU @ 2.30GHz (skylake_avx512), Python 3.6.8
See https://gist.github.com/dc1e360557093ac4e3ecc678c8578223 for a full test report.

[boegel]

Test report by @boegel
SUCCESS
Build succeeded for 2 out of 2 (2 easyconfigs in total)
node3560.doduo.os - Linux RHEL 8.2, x86_64, AMD EPYC 7552 48-Core Processor (zen2), Python 3.6.8
See https://gist.github.com/06af706f9cc066a8cd50ea1ff5c34358 for a full test report.

[boegelbot]

Test report by @boegelbot
SUCCESS
Build succeeded for 2 out of 2 (2 easyconfigs in total)
cns1 - Linux rocky linux 8.4, x86_64, Intel(R) Xeon(R) CPU E5-2667 v3 @ 3.20GHz (haswell), Python 3.6.8
See https://gist.github.com/f8556f920a5df3d4295f2542e34c7a65 for a full test report.

[boegel]

Going in, thanks @casparvl!