[MAINT] checkout tags for doc deployment

fixes missing version information in docs

Author: orbeckst

.github/workflows/docs.yaml

@@ -19,6 +19,8 @@ jobs:
 
     steps:
     - uses: actions/checkout@v2
+      with:
+        fetch-depth: 0         
 
     - name: setup_miniconda
       uses: conda-incubator/setup-miniconda@v2