unconfused myself, add manta as dependency to more parts of CI

.github/workflows/functional_sim.yml

@@ -5,5 +5,19 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v3
+
+      - name: Install Manta from Source
+        run: |
+          pip install setuptools --upgrade
+
+          # omitting the following commmand causes the version of setuptools
+          # used by python to get confused, and it doesn't detect the name
+          # or version of the package from pyproject.toml - so the following
+          # workaround is used:
+          # https://github.com/pypa/setuptools/issues/3269#issuecomment-1254507377
+          export DEB_PYTHON_INSTALL_LAYOUT=deb_system
+
+          python3 -m pip install .
+
       - run: sudo apt install iverilog
       - run: make functional_sim