Release v1r20

2023-09-13 Detector v1r20

This version uses LCG 103 with ROOT 6.28.00.

This version is released on the `` branch. Built relative to Detector v1r19, with the following changes:

• FT | Add a header method and a check that a sourceID is FT, !429 (merged) (@lohenry)
• FT | Enforce centre-to-edge convention on the global indices of FT mat and sipm, !423 (merged) (@lohenry)