Update package to upstream release 0.31 plus cleanups
    
    This commit includes the following changes from the update to upstream
    release 0.31:
      - mount-image-callback: mount with -o 'rw' or -o 'ro'
        (LP: #1663722)
      - mount-image-callback: run blockdev and udevadm settle on nbd devices.
        (LP: #1741096, 1741300)
      - mount-image-callback: Drop support for mounting lxd containers.
        (LP: #1715994)
      - growpart: fix bug that stopped GPT disks from being grown past 2TB.
        (LP: #1762748)
      - mount-image-callback: mention --help and -C/--cd-mountpoint in Usage
      - growpart: fix bug when resizing a middle partition with sgdisk
        (LP: #1706751) [Fred De Backer]
      - growpart: Resolve symbolic links before operating.
        [Kevin Locke] (LP: #1744406)
      - growpart: fix bug occurring if start sector and size were the same.
        [Lars Kellogg-Stedman] (LP: #1807171)
      - debian/control: drop Suggests on lxc1
      - debian/tests/control: add test growpart-start-matches-size.
      - White space cleanup.  Remove trailing space and tabs.
    
    Additionally:
      - Change the requirements from python2 to python3.
      - Drop the python2-paramiko requirement which was only used by the
        cloud-run-instances script which is no longer included.
      - Drop the cloud-run-instances manpage.
    
    Signed-off-by: Juerg Haefliger <juergh@gmail.com>