hpcng/singularity: Singularity 3.7.1

Bug Fixes Accommodate /sys/fs/selinux mount changes on kernel 5.9+. Fix loop devices file descriptor leak when shared loop devices is enabled. Use MaxLoopDevices variable from config file in all appropriate locations. Use -buildmode=default (non pie) on ppc64le to prevent crashes when using plugins. Remove spurious warning in parseTokenSection() e2e test fixes for new kernels, new unsquashfs version. Show correct web URI for detached builds against alternate remotes. Thanks / Reporting Bugs Thanks to our contributors for code, feedback and, testing efforts! As always, please report any bugs to: https://github.com/hpcng/singularity/issues/new If you think that you've discovered a security vulnerability please report it to: security@sylabs.io Have fun! Downloads Please use the singularity-3.7.1.tar.gz download below to obtain and install Singularity 3.7.1. The GitHub auto-generated 'Source Code' downloads do not include required dependencies etc