[FIX] packaging: List all package versions in APT repositories

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#53888

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

setup/package.py

@@ -119,7 +119,7 @@ def gen_deb_package(args, published_files):
         shutil.copy(pub_file_path, temp_path)
 
     commands = [
-        (['dpkg-scanpackages', '.'], "Packages"),  # Generate Packages file
+        (['dpkg-scanpackages', '--multiversion', '.'], "Packages"),  # Generate Packages file
         (['dpkg-scansources', '.'], "Sources"),  # Generate Sources file
         (['apt-ftparchive', 'release', '.'], "Release")  # Generate Release file
     ]