Drop backward compatibility hack for fmtlib < 8
I implemented a hack to fix builds against fmt < 8 (see !1455 (comment 6781515)).
In %v37r0 we update the LCG baseline version used in CI tests and at that point we can revert the hack.
We should also evaluate
- the changes in !1409 (merged)
- 6979814d
- d36d1a86
Edited by Marco Clemencic