INSTALL: Update Debian package status

Also, make the note generic, to omit the need to update it "constantly".

Closes #76
9 jobs for 76-install-update-debian-status in 2 minutes and 20 seconds (queued for 2 seconds)
Status Job ID Name Coverage
  Linting
passed #101425
linting:bandit

00:00:19

passed #101428
linting:mypy

00:00:19

passed #101427
linting:pyflakes

00:00:21

passed #101426
linting:pylint

00:00:28

 
  Test
passed #101429
tests:archlinux

00:01:22

passed #101430
tests:debian

00:01:21

98.0%
failed #101431
allowed to fail
tests:debian_with_bubblewrap

00:01:50

passed #101432
tests:fedora

00:01:25

failed #101433
allowed to fail
tests:gentoo

00:01:18

 
Name Stage Failure
failed
tests:debian_with_bubblewrap Test
  File "/usr/lib/python3.7/subprocess.py", line 487, in run
output=stdout, stderr=stderr)
subprocess.CalledProcessError: Command '['/usr/bin/bwrap', '--ro-bind', '/usr', '/usr', '--ro-bind', '/lib', '/lib', '--ro-bind', '/lib64', '/lib64', '--ro-bind', '/bin', '/bin', '--ro-bind', '/sbin', '/sbin', '--ro-bind', '/builds/jvoisin/mat2', '/builds/jvoisin/mat2', '--ro-bind', '/etc/ld.so.cache', '/etc/ld.so.cache', '--dev', '/dev', '--chdir', '/builds/jvoisin/mat2', '--unshare-all', '--new-session', '--ro-bind', '/tmp/tmpoodkuu5v/tests/data/dirty.jpg', '/tmp/tmpoodkuu5v/tests/data/dirty.jpg', '/usr/bin/exiftool', '-json', '/tmp/tmpoodkuu5v/./tests/data/dirty.jpg']' returned non-zero exit status 1.

----------------------------------------------------------------------
Ran 128 tests in 95.219s

FAILED (errors=2)
ERROR: Job failed: exit code 1
failed
tests:gentoo Test
  File "/builds/jvoisin/mat2/tests/test_libmat2.py", line 137, in test_flac
self.assertEqual(meta['Cover 0'], {'Comment': 'Created with GIMP'})
AssertionError: 'harmful data' != {'Comment': 'Created with GIMP'}

----------------------------------------------------------------------
Ran 128 tests in 62.127s

FAILED (failures=12, errors=10)
ERROR: Job failed: exit code 1