[FIX] packaging: remove libsass dependency in debian package

A dependency to libsass was added in debian package and in the docker
file. The Odoo nightly builds of the deb package was failing because
this lib is named libsass0 in Debian.

Finally, this dependency is not required because python3-libsass already depends on libsass0.

debian/control

@@ -14,7 +14,6 @@ Depends:
  ${misc:Depends},
  ${python3:Depends},
  adduser,
- libsass,
  lsb-base,
  postgresql-client,
  python3-babel,

setup/package.dfdebian

@@ -17,7 +17,6 @@ RUN apt-get update -qq &&  \
     apt-get upgrade -qq -y && \
     apt-get install \
         adduser \
-        libsass \
         postgresql \
         postgresql-client \
         python3 \