Merge pull request matplotlib#26204 from QuLogic/add-tzdata

ci: Add tzdata to nightly builds

Author: story645

.github/workflows/tests.yml

@@ -261,7 +261,7 @@ jobs:
           github.event_name == 'schedule' &&
           matrix.name-suffix != '(Minimum Versions)'
         run: |
-          python -m pip install pytz  # Must be installed for Pandas.
+          python -m pip install pytz tzdata  # Must be installed for Pandas.
           python -m pip install \
             --index-url https://pypi.anaconda.org/scientific-python-nightly-wheels/simple \
             --upgrade --only-binary=:all: numpy pandas