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 c7b03324ee57eb42ed1a7b4eba8a0f64776d157a..a7e725866f217909572bbfe0623370a921308311 100644 (file)
--- a/.github/workflows/run-tests.yaml
+++ b/.github/workflows/run-tests.yaml
@@ -56,7 +56,7 @@ 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"