Add validation action

...as documented in https://github.com/skohub-io/shapes#add-validation-in-a-vocabulary-repository

.github/workflows/main.yaml

@@ -0,0 +1,48 @@
+name: Validate TTL Files
+
+on: [push]
+
+jobs:
+  check-for-warnings:
+    name: Check for Warnings
+    runs-on: ubuntu-latest
+    steps:
+    - name: Checkout repository
+      uses: actions/checkout@v3
+
+    - name: Check for Warnings
+      run: |
+        curl -s https://raw.githubusercontent.com/skohub-io/shapes/main/scripts/checkForWarning.rq >> checkForWarning.rq
+        find . -type f -name '*.ttl' | while read file; do
+          # Adjust the file path to remove the './' part
+          adjusted_file_path=$(echo "$file" | sed 's|^./||')
+          echo "Processing $adjusted_file_path with Docker..."
+          docker run --rm -v "$(pwd)/$adjusted_file_path:/rdf/test.ttl" skohub/jena:4.6.1 shacl validate --shapes https://raw.githubusercontent.com/skohub-io/shapes/main/skohub.shacl.ttl --data /rdf/test.ttl >> result.ttl
+          validation_result="$(docker run --rm --mount type=bind,source=./checkForWarning.rq,target=/rdf/checkForViolation.rq --mount type=bind,source=./result.ttl,target=/rdf/result.ttl skohub/jena:4.6.1 arq --data /rdf/result.ttl --query /rdf/checkForViolation.rq)"
+          echo $validation_result
+          lines=$(echo "$validation_result" | wc -l )
+          # Correct validation has 4 lines of output
+          [[ ${lines} -eq 4 ]] || exit 1
+        done
+
+  check-for-errors:
+    name: Check for Errors
+    runs-on: ubuntu-latest
+    steps:
+    - name: Checkout repository
+      uses: actions/checkout@v3
+
+    - name: Check for Errors
+      run: |
+        curl -s https://raw.githubusercontent.com/skohub-io/shapes/main/scripts/checkForViolation.rq >> checkForViolation.rq
+        find . -type f -name '*.ttl' | while read file; do
+          # Adjust the file path to remove the './' part
+          adjusted_file_path=$(echo "$file" | sed 's|^./||')
+          echo "Processing $adjusted_file_path with Docker..."
+          docker run --rm -v "$(pwd)/$adjusted_file_path:/rdf/test.ttl" skohub/jena:4.6.1 shacl validate --shapes https://raw.githubusercontent.com/skohub-io/shapes/main/skohub.shacl.ttl --data /rdf/test.ttl >> result.ttl
+          validation_result="$(docker run --rm --mount type=bind,source=./checkForViolation.rq,target=/rdf/checkForViolation.rq --mount type=bind,source=./result.ttl,target=/rdf/result.ttl skohub/jena:4.6.1 arq --data /rdf/result.ttl --query /rdf/checkForViolation.rq)"
+          echo $validation_result
+          lines=$(echo "$validation_result" | wc -l )
+          # Correct validation has 4 lines of output
+          [[ ${lines} -eq 4 ]] || exit 1
+        done