add generated schema and github workflow

.github/scripts/schema.py

@@ -16,14 +16,15 @@
 
 """Creation of schema for rockcraft.yaml."""
 import json
+import os
 import sys
 from typing import TYPE_CHECKING
 
 from craft_parts import Part
 
-sys.path.append("rockcraft")
+script_dir = os.path.dirname(os.path.realpath(__file__))
+sys.path.append(os.path.join(script_dir, "../../"))
 
-from rockcraft import errors  # noqa: E402
 from rockcraft.models.project import Project  # noqa: E402
 
 if TYPE_CHECKING:

.github/workflows/schema.yaml

@@ -0,0 +1,26 @@
+name: schema
+on: [pull_request]
+
+jobs:
+  generate-schema:
+    runs-on: ubuntu-22.04
+
+    steps:
+      - name: Checkout rockcraft
+        uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+
+      - name: Set up Python
+        uses: actions/setup-python@v5
+        with:
+          python-version: '3.10'
+
+      - name: Install requirements
+        run: pip install -r requirements.txt
+
+      - name: Run generator script
+        run: python .github/scripts/schema.py > generated_schema.json
+
+      - name: Check with stored schema
+        run: diff generated_schema.json schemas/rockcraft_schema.json > /dev/null