test_webapp: avoid locale dependency for released_suite API test
test_webapp: avoid locale dependency for released_suite API test

To do so, replace hard-coded date string with datetime object

Also, resolve some flake8 issues

Signed-off-by: Stefano Zacchiroli <d7cdf09fc0f0426e98c9978ee42da5d61fa54986@upsilon.cc>

devoxel/debsources,vivekanand1101/debsources,sophiejjj/debsources,zacchiro/debsources,devoxel/debsources,matthieucan/debsources,sophiejjj/debsources,zacchiro/debsources,sophiejjj/debsources,vivekanand1101/debsources,vivekanand1101/debsources,oorestisime/debsources,Debian/debsources,clemux/debsources,Debian/debsources,sophiejjj/debsources,oorestisime/debsources,Debian/debsources,zacchiro/debsources,oorestisime/debsources,matthieucan/debsources,Debian/debsources,matthieucan/debsources,zacchiro/debsources,clemux/debsources,zacchiro/debsources,clemux/debsources,Debian/debsources,vivekanand1101/debsources,matthieucan/debsources,sophiejjj/debsources,vivekanand1101/debsources,clemux/debsources,devoxel/debsources,matthieucan/debsources,devoxel/debsources,oorestisime/debsources,devoxel/debsources,oorestisime/debsources,clemux/debsources