fix pipenv

Author: dmitry-shibanov

.github/workflows/e2e-cache.yml

@@ -57,7 +57,7 @@ jobs:
           # } else {
           #   pipenv install flake8 --python ${{ matrix.python-version }}
           # }
-          pipenv install flake8
+          pipenv install --system flake8
   python-pip-dependencies-caching-path:
     name: Test pip (Python ${{ matrix.python-version}}, ${{ matrix.os }})
     runs-on: ${{ matrix.os }}
@@ -103,4 +103,4 @@ jobs:
           # } else {
           #   pipenv install flake8 --python ${{ matrix.python-version }}
           # }
-          pipenv install flake8
+          pipenv install --system flake8