add missing dependencies for OpenPIV + switch to PythonBundle easyblock and include progressbar2 as extension

[boegel]

(created using eb --new-pr)
missing deps uncovered by fixed bug in easyblock (see easybuilders/easybuild-easyblocks#2114)

edit: note: make sure you have an updated Python installation, since dask required sortedcontainers to be included (see #10969)

[boegel]

Test report by @boegel
SUCCESS
Build succeeded for 5 out of 5 (5 easyconfigs in this PR)
node3151.skitty.os - Linux centos linux 7.8.2003, x86_64, Intel(R) Xeon(R) Gold 6140 CPU @ 2.30GHz (skylake_avx512), Python 3.6.8
See https://gist.github.com/211ea5debaf5d5e25974379e167980d5 for a full test report.

[boegel]

Test report by @boegel
SUCCESS
Build succeeded for 5 out of 5 (5 easyconfigs in this PR)
generoso - Linux centos linux 8.2.2004, x86_64, Intel(R) Xeon(R) CPU E5-2667 v3 @ 3.20GHz (haswell), Python 3.6.8
See https://gist.github.com/fcdcd07de68d7e76c1703622b25023d4 for a full test report.

[smoors]

Test report by @smoors
FAILED
Build succeeded for 3 out of 6 (5 easyconfigs in this PR)
node254.hydra.os - Linux centos linux 7.7.1908, x86_64, Intel(R) Xeon(R) CPU E5-2683 v4 @ 2.10GHz (broadwell), Python 2.7.5
See https://gist.github.com/84434cb3525e349489482aae209c5cd8 for a full test report.

[migueldiascosta]

Test report by @migueldiascosta
FAILED
Build succeeded for 2 out of 5 (5 easyconfigs in this PR)
sms - Linux centos linux 7.6.1810, x86_64, AMD EPYC 7601 32-Core Processor (zen), Python 2.7.5
See https://gist.github.com/510326ec7a3bf9b164bb65958d26d76f for a full test report.

[migueldiascosta]

Test report by @migueldiascosta
SUCCESS
Build succeeded for 5 out of 5 (5 easyconfigs in this PR)
sms - Linux centos linux 7.6.1810, x86_64, AMD EPYC 7601 32-Core Processor (zen), Python 2.7.5
See https://gist.github.com/240733993084402e6b56a546c85069d2 for a full test report.

[boegel]

@smoors You need to make sure your Python installation includes sortedcontainers, see note in PR descr.

[smoors]

Test report by @smoors
SUCCESS
Build succeeded for 6 out of 6 (5 easyconfigs in this PR)
node253.hydra.os - Linux centos linux 7.7.1908, x86_64, Intel(R) Xeon(R) CPU E5-2650 v4 @ 2.20GHz (broadwell), Python 2.7.5
See https://gist.github.com/9dc532a4c58acbfe08e38e4f317beca7 for a full test report.

[smoors]

lgtm

[smoors]

Going in, thanks @boegel!