Replace $schema enum by $schema pattern

The $schema attribute defines which schema versions are compatible with this schema. Software systems that validate a SET payload against this schema should not only accept SET payloads which exactly match this schema version but also accept SET payloads that validate against compatible schema versions (same major version)

spec/set-payload.schema.json

@@ -6,9 +6,9 @@
   "type": "object",
   "properties": {
     "$schema": {
-      "description": "URI des Schemas, dem dieser Security Event Token entspricht.",
+      "description": "URI des Schemas, dem dieser Security Event Token entspricht. Zulässig sind alle Schema-URLs mit enthaltener Version 1.x.y, wobei x und y beliebige Minor- und Patch-Versionen gemäß https://semver.org/ sein können.",
       "type": "string",
-      "enum": [ "https://schema.fitko.de/fit-connect/set-payload/SCHEMA_VERSION/set-payload.schema.json" ]
+      "pattern": "^https:/\\/schema\\.fitko\\.de\\/fit-connect\\/set-payload\\/1\\.\\d+\\.\\d+\\/set-payload\\.schema\\.json$"
     },
     "jti": {
       "description": "Die JWT ID (jti) ist eine eindeutige UUID für das SET.",