renovate: don't update Go toolchain directive

Author: katexochen

renovate.json5

@@ -66,6 +66,13 @@
         "patch",
       ],
     },
+    {
+      // Disable Go toolchain directive updates in go.mod.
+      // These don't make any sense, we use the toolchain available in nixpkgs.
+      matchManagers: [ "gomod" ],
+      matchDepNames: [ "toolchain" ],
+      enabled: false,
+    },
     {
       // Group update of GitHub actions dependencies.
       matchManagers: [ "github-actions" ],