Avoid using broken pip 2020-resolver (#2904)

Apparently new resolved can get into endless loops of building packages.

Related: pypa/pip#8713

.github/workflows/tox.yml

@@ -16,6 +16,8 @@ jobs:
   build:
     name: ${{ matrix.tox_env }}
     runs-on: ubuntu-latest
+    # limit potential endless looks like we had with build-containers
+    timeout-minutes: 20
     strategy:
       fail-fast: false
       matrix:

Dockerfile

@@ -76,12 +76,11 @@ molecule-vagrant \
 "
 
 # https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=917006
-RUN PIP_USE_FEATURE=2020-resolver python3 -m pip install -U wheel pip setuptools
+RUN python3 -m pip install -U wheel pip setuptools
 
 ADD . .
 
 RUN \
-PIP_USE_FEATURE=2020-resolver \
 python3 -m pip wheel \
 -w dist --no-build-isolation \
 ".[${MOLECULE_EXTRAS}]" testinfra ${MOLECULE_PLUGINS}
@@ -186,7 +185,6 @@ COPY --from=molecule-builder \
 /usr/src/molecule/dist
 
 RUN \
-PIP_USE_FEATURE=2020-resolver \
 python3 -m pip install \
 ${PIP_INSTALL_ARGS} \
 "molecule[${MOLECULE_EXTRAS}]" testinfra ${MOLECULE_PLUGINS} && \