additionally update PYTHONPATH

Author: patapenka-alexey

.github/workflows/packing.yml

@@ -558,6 +558,8 @@ jobs:
           . .venv/bin/activate
           apt install -y `pwd`/deb_dist/python3-tarantool_*.deb
           ls -la /usr/lib/python3/dist-packages/tarantool
+          export PYTHONPATH=$PYTHONPATH:/usr/lib/python3/dist-packages/tarantool:/usr/lib/python3/dist-packages/tarantool/
+          echo $PYTHONPATH
           make test-pure-install
         if: matrix.target.dist == 'bookworm' || matrix.target.dist == 'noble'