Catch2 version too old for build on Fedora 35

The tests don't compile on Fedora 35. Apparently a recent change in glibc creates a conflict with catch2, see https://github.com/catchorg/Catch2/issues/2178

Fix: update to latest catch2

added Build System Testing labels

created merge request !423 (merged) to address this issue

mentioned in merge request !423 (merged)

see also #481 (closed)

Ha, seems I missed that one.

mentioned in commit 340f0a1a

closed with merge request !423 (merged)