Update dependency @antora/site-generator to v3.1.12

Author: xdev-renovate

docs/package.json

@@ -4,6 +4,6 @@
   },
   "devDependencies": {
     "@antora/cli": "3.1.10",
-    "@antora/site-generator": "3.1.10"
+    "@antora/site-generator": "3.1.12"
   }
 }