Fix broken docs coverage workflows (#246)

Author: stes

.github/workflows/build.yml

@@ -68,6 +68,10 @@ jobs:
         run: |
           make codespell
 
+      - name: Check the documentation coverage
+        run: |
+          make interrogate
+
       - name: Check CITATION.cff validity
         run: |
           cffconvert --validate

.github/workflows/doc-coverage.yml

@@ -106,6 +106,7 @@ dev =
     pytest-sphinx
     tables
     licenseheaders
+    interrogate
     # TODO(stes) Add back once upstream issue
     # https://github.com/PyCQA/docformatter/issues/119
     # is resolved.