Bump version to 5.12

Author: wawanbreton

conandata.yml

@@ -1,4 +1,4 @@
-version: "5.11.0"
+version: "5.12.0-alpha.0"
 commit: "unknown"
 requirements:
   - "scripta/[>=1.1.0]@ultimaker/testing"
@@ -9,4 +9,4 @@ requirements_arcus:
 requirements_plugins:
   - "curaengine_grpc_definitions/0.3.2"
 requirements_cura_resources:
-  - "cura_resources/5.11.0"
+  - "cura_resources/5.12.0-alpha.0"