add CWL JSON schema + 'json_schema_invalid' tag (closes #253) + validation tests (2 failed related to #251)

Author: fmigneault

.github/workflows/ci.yml

@@ -35,3 +35,8 @@ jobs:
 
       - name: Validate CWL documents
         run: ./run_test.sh --self
+
+      - name: Validate JSON schema document
+        run: |
+          pip install -r ./requirements-jsonschema-test.txt
+          pytest tests/json_schema

conformance_tests.yaml

@@ -2633,7 +2633,7 @@
   tool: tests/timelimit2.cwl
   id: timelimit_invalid
   doc: Test invalid time limit value
-  tags: [ command_line_tool, timelimit ]
+  tags: [ command_line_tool, timelimit, json_schema_invalid ]
 
 - job: tests/empty.json
   output: {}
@@ -3472,4 +3472,4 @@
       basename: file.txt
       size: 14
       checksum: sha1$0074b1841ab5103cc0442f739d9fb41a33b602ee
-  tags: [ step_input, workflow ]
+  tags: [ step_input, workflow ]