update blob to raw

versions/sip-schema-d1.json

 {
     "$schema": "https://json-schema.org/draft/2020-12/schema",
-    "$id": "https://gitlab.cern.ch/digitalmemory/sip-spec/-/blob/main/versions/sip-schema-d1.json",
+    "$id": "https://gitlab.cern.ch/digitalmemory/sip-spec/-/raw/main/versions/sip-schema-d1.json",
     "title": "SIP high level metadata",
     "description": "High level metadata defining a SIP accepted by CERN Digital Memory OAIS.",
     "type": "object",

versions/sip-schema-v1.json

 {
     "$schema": "https://json-schema.org/draft/2020-12/schema",
-    "$id": "https://gitlab.cern.ch/digitalmemory/sip-spec/-/blob/main/versions/sip-schema-v1.json",
+    "$id": "https://gitlab.cern.ch/digitalmemory/sip-spec/-/raw/main/versions/sip-schema-v1.json",
     "title": "SIP high level metadata",
     "description": "High level metadata defining a SIP accepted by CERN Digital Memory OAIS.",
     "type": "object",