[FIX] packaging: install python3-setuptools in docker

Since 5952928b, the python3-mock debian package is removed from the
Dockerfile used to build the Debian package. This prevent the Odoo
Debian package to be built.

The python3-mock debian package has an inderect dependency on
python3-setuptools which is necessary to build the package.

With this commit, the dependency is explicitely set in the Dockerfile.

closes odoo/odoo#49278

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

setup/package.dfdebian

@@ -47,6 +47,7 @@ RUN apt-get update -qq &&  \
         python3-reportlab \
         python3-requests \
         python3-serial \
+        python3-setuptools \
         python3-stdnum \
         python3-suds \
         python3-tz \