Revert "No need to download baseline images"

`test_image` needs baseline images.

This reverts commit a6ee0e5.

Author: seisman

.github/workflows/ci_tests_backward.yaml

@@ -65,7 +65,7 @@ jobs:
         run: |
           mamba install gmt=${{ matrix.gmt_version }} numpy \
                         pandas xarray netCDF4 packaging geopandas \
-                        build make pytest>=6.0 \
+                        build dvc make pytest>=6.0 \
                         pytest-cov pytest-doctestplus pytest-mpl sphinx-gallery
 
       # Show installed pkg information for postmortem diagnostic
@@ -90,6 +90,12 @@ jobs:
           touch ~/.gmt/server/gmt_data_server.txt ~/.gmt/server/gmt_hash_server.txt
           ls -lhR ~/.gmt
 
+      # Pull baseline image data from dvc remote (DAGsHub)
+      - name: Pull baseline image data from dvc remote
+        run: |
+          dvc pull --verbose
+          ls -lhR pygmt/tests/baseline/
+
       # Install the package that we want to test
       - name: Install the package
         run: make install