fix: Add missing protobuf compiler to GHA

Author: ruivieira

.github/workflows/python-tests.yaml

@@ -35,6 +35,11 @@ jobs:
             uv pip install pytest
           fi
 
+      - name: Install protobuf compiler
+        run: |
+          sudo apt-get update
+          sudo apt-get install -y protobuf-compiler
+
       - name: Generate protobuf stubs
         run: |
           source .venv/bin/activate