testing/librewolf: fix checksum
Some contents of https://gitlab.com/api/v4/projects/32320088/packages/generic/librewolf-source/121.0.1-1/librewolf-121.0.1-1.source.tar.gz apparently changed since !58896 (merged).
Some contents of https://gitlab.com/api/v4/projects/32320088/packages/generic/librewolf-source/121.0.1-1/librewolf-121.0.1-1.source.tar.gz apparently changed since !58896 (merged).