Fix finally helper with C++20

adding a test to make sure we compile an instantiation of it

changed milestone to %v37r0

assigned to @clemenci

added lhcb-gaudi-head lhcb-lcg-dev3lhcb lhcb-lcg-dev4lhcb labels

• [2023-07-14 10:21] Validation started with lhcb-lcg-dev4lhcb#219
• [2023-07-15 08:52] Validation started with lhcb-lcg-dev4lhcb#220
• [2023-07-15 09:09] Validation started with lhcb-gaudi-head#3626
• [2023-07-15 09:19] Validation started with lhcb-lcg-dev3lhcb#212
• [2023-07-15 09:27] Validation started with lhcb-run2-gaudi-head#580
• [2023-07-16 00:03] Validation started with lhcb-gaudi-head#3627
• [2023-07-16 00:13] Validation started with lhcb-lcg-dev3lhcb#213
• [2023-07-16 00:14] Validation started with lhcb-lcg-dev4lhcb#221
• [2023-07-16 00:22] Validation started with lhcb-run2-gaudi-head#581
• [2023-07-17 00:03] Validation started with lhcb-gaudi-head#3628
• [2023-07-17 00:14] Validation started with lhcb-lcg-dev3lhcb#214
• [2023-07-17 00:15] Validation started with lhcb-lcg-dev4lhcb#222
• [2023-07-17 00:27] Validation started with lhcb-run2-gaudi-head#582

approved this merge request

merged

mentioned in commit 0aad251b