Singularity installation fails with missing dependency

[adswa]

The Appveyor run in #262 failed during setup with

Preparing to unpack /tmp/singularity-ce.deb ...
Unpacking singularity-ce (4.1.1-focal) ...
dpkg: dependency problems prevent configuration of singularity-ce:
 singularity-ce depends on fuse2fs; however:
  Package fuse2fs is not installed.
dpkg: error processing package singularity-ce (--install):
 dependency problems - leaving unconfigured
Processing triggers for man-db (2.9.1-1) ...
Errors were encountered while processing:
 singularity-ce
Command exited with code 1
Running "on_finish" scripts

Adding this dependency should resolve the issue.