bug: mypy should ignore files in test/ (#3894)

* exclude files in test/

* verify that the CI ignores test files

* dont fail in case of no files

.github/workflows/tests.yml

@@ -93,7 +93,9 @@ jobs:
       run: |
         for file in ${{ steps.files.outputs.all_changed_files }}; do
           if [[ $file == *.py ]]; then
-            changed_files="$changed_files $file"
+            if [[ $file != test/* ]]; then
+              changed_files="$changed_files $file"
+            fi
           fi
         done
         echo "changed_files=$changed_files" >> $GITHUB_OUTPUT
@@ -104,6 +106,7 @@ jobs:
         pythonVersion: 3.8   # Literals and mypy just don't work well together.
 
     - name: Mypy
+      if: steps.python-files.outputs.changed_files
       run: |
         mkdir .mypy_cache/
         mypy ${{ steps.python-files.outputs.changed_files }}

test/conftest.py

@@ -35,7 +35,6 @@ from haystack.document_stores import (
     OpenSearchDocumentStore,
     GraphDBKnowledgeGraph,
     FAISSDocumentStore,
-    SQLDocumentStore,
 )
 from haystack.nodes import (
     BaseReader,