When building the package list of the APT repository, dpkg-scanpackages
reports the following and only output the latest package information in
the Packages file:

```
dpkg-scanpackages: warning: Packages with multiple instances but no --multiversion specified:
dpkg-scanpackages: warning: ./odoo_13.0.20191002_all.deb
dpkg-scanpackages: warning: ./odoo_13.0.20191003_all.deb
[...]
dpkg-scanpackages: warning: ./odoo_13.0.20200630_all.deb
```

Having only the latest version listed in the Packages file makes it
impossible to tell apt to use a specific version through apt-pinning.
It also makes it impossible to revert to a previous version if a
regression is caused by an update.

For these reasons, tell dpkg-scanpackages to include all versions of the
odoo package in the Packages file it generates.

closes odoo/odoo#54302

X-original-commit: f41c00a8
Signed-off-by: Christophe Monniez (moc) <moc@odoo.com>