Update main/version.json to 26-dev

PiperOrigin-RevId: 580259174

version.json

@@ -1,17 +1,17 @@
 {
-  "25.x": {
-    "protoc_version": "25.0-dev",
+  "main": {
+    "protoc_version": "26-dev",
     "lts": false,
     "date": "2023-11-01",
     "languages": {
-      "cpp": "4.25.0-dev",
-      "csharp": "3.25.0-dev",
-      "java": "3.25.0-dev",
-      "javascript": "3.25.0-dev",
-      "objectivec": "3.25.0-dev",
-      "php": "3.25.0-dev",
-      "python": "4.25.0-dev",
-      "ruby": "3.25.0-dev"
+      "cpp": "4.26-dev",
+      "csharp": "3.26-dev",
+      "java": "3.26-dev",
+      "javascript": "3.26-dev",
+      "objectivec": "3.26-dev",
+      "php": "3.26-dev",
+      "python": "4.26-dev",
+      "ruby": "3.26-dev"
     }
   }
 }