chore: disable dependency updates for pre-release versions and kord

* pre-release versions are usually suffixed with `-next.1`, `-dev.1` or something similar. we're excluding those from the dependency updates
* we're currently relying on the graalvm snapshot build. waiting until there's progress on kordlib/kord#786

.github/renovate.json

@@ -9,5 +9,17 @@
         ":labels(dependencies)",
         "group:allNonMajor",
         "schedule:weekly"
+    ],
+    "packageRules": [
+        {
+            "matchPackagePatterns": "*",
+            "allowedVersions": "!/-.+\\.[0-9]+$/"
+        },
+        {
+            "matchPackagePatterns": [
+                "dev.kord:kord-core"
+            ],
+            "enabled": false
+        }
     ]
 }