Pull baseline images from the gmt-6.4 branch only for scheduled jobs (#1882)

Author: seisman

.github/workflows/ci_tests_dev.yaml

@@ -106,14 +106,23 @@ jobs:
 
       # Pull baseline image data from dvc remote (DAGsHub)
       - name: Pull baseline image data from dvc remote
+        if: github.event_name == 'schedule'
         run: |
           ORIGINAL_BRANCH=$(git branch --show-current)
           # Pull down GMT 6.4 baseline images from the gmt-6.4 branch
+          # https://github.com/GenericMappingTools/pygmt/pull/1883
           git checkout gmt-6.4
           dvc pull
           ls -lhR pygmt/tests/baseline/
           git checkout ${ORIGINAL_BRANCH}
 
+      # Pull baseline image data from dvc remote (DAGsHub)
+      - name: Pull baseline image data from dvc remote
+        if: github.event_name != 'schedule'
+        run: |
+          dvc pull
+          ls -lhR pygmt/tests/baseline/
+
       # Build and install latest GMT from GitHub
       - name: Install GMT ${{ matrix.gmt_git_ref }} branch (Linux/macOS)
         run: curl https://raw.githubusercontent.com/GenericMappingTools/gmt/master/ci/build-gmt.sh | bash