CI(GHActions): Ensure `pip` only if needed

This is to work around a problem in conda with Python 3.7 -
it brings in wrong version of `setuptools` incompatible with Python 3.7.

diff --git a/.github/workflows/run-tests.yaml b/.github/workflows/run-tests.yaml
index 61d2d6fcc0dff0b4461bfe8998f9fb72acaac613..34bb96b48545c0fb266f9116b5771eb5df6e1830 100644 (file)
--- a/.github/workflows/run-tests.yaml
+++ b/.github/workflows/run-tests.yaml
@@ -45,7 +45,7 @@ jobs:
       - name: Install dependencies
         run: |
           python --version
-          python -m ensurepip
+          python -m pip || python -m ensurepip --default-pip --upgrade
           python -m pip install --upgrade pip setuptools wheel
           pip --version
           pip install --upgrade virtualenv "tox >= 3.15, < 4"