add missing GSL dependency for casacore 3.4.0

[t1mk1k]

Running tests for casacore 3.5.0, we discovered that GSL was missing as a dependency for casacore 3.4.0

The test report:
https://gist.github.com/boegelbot/3e68e69278124da4ab5ab1b64d497db4

[Micket]

@boegelbot please test @ jsc-zen2

[boegelbot]

@Micket: Request for testing this PR well received on jsczen2l1.int.jsc-zen2.easybuild-test.cluster

PR test command 'EB_PR=19042 EB_ARGS= EB_REPO=easybuild-easyconfigs /opt/software/slurm/bin/sbatch --mem-per-cpu=4000M --job-name test_PR_19042 --ntasks=8 ~/boegelbot/eb_from_pr_upload_jsc-zen2.sh' executed!

• exit code: 0
• output:

Submitted batch job 3585

Test results coming soon (I hope)...

Details

- notification for comment with ID 1771818187 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).

[Micket]

Test report by @Micket
SUCCESS
Build succeeded for 1 out of 1 (1 easyconfigs in total)
alvis-c1 - Linux Rocky Linux 8.8, x86_64, Intel Xeon Processor (Skylake), Python 3.6.8
See https://gist.github.com/Micket/4c8b0f34942bb2b17ff243cd5f642f56 for a full test report.

[boegelbot]

Test report by @boegelbot
SUCCESS
Build succeeded for 1 out of 1 (1 easyconfigs in total)
jsczen2c1.int.jsc-zen2.easybuild-test.cluster - Linux Rocky Linux 8.5, x86_64, AMD EPYC 7742 64-Core Processor (zen2), Python 3.6.8
See https://gist.github.com/boegelbot/2eab62fdd176ef1050c3e18cc8ef720b for a full test report.

[Micket]

@boegelbot please test @ generoso

[boegelbot]

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

PR test command 'EB_PR=19042 EB_ARGS= EB_CONTAINER= EB_REPO=easybuild-easyconfigs /opt/software/slurm/bin/sbatch --job-name test_PR_19042 --ntasks=4 ~/boegelbot/eb_from_pr_upload_generoso.sh' executed!

• exit code: 0
• output:

Submitted batch job 11983

Test results coming soon (I hope)...

Details

- notification for comment with ID 1771830188 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).

[boegelbot]

Test report by @boegelbot
SUCCESS
Build succeeded for 1 out of 1 (1 easyconfigs in total)
cns2 - Linux Rocky Linux 8.5, x86_64, Intel(R) Xeon(R) CPU E5-2667 v3 @ 3.20GHz (haswell), Python 3.6.8
See https://gist.github.com/boegelbot/0388a20e49ee75a8aa9d81608a325e89 for a full test report.

[Micket]

lgtm