github-copilot-cli: fix mcp integration

MCP servers require the args in json, even if not configured.

tests/modules/programs/github-copilot-cli/expected-mcp-integration-config.json

@@ -14,6 +14,14 @@
       ],
       "type": "local"
     },
+    "fetch": {
+      "args": [],
+      "command": "mcp-server-fetch",
+      "tools": [
+        "*"
+      ],
+      "type": "local"
+    },
     "filesystem": {
       "args": [
         "-y",

tests/modules/programs/github-copilot-cli/mcp-integration.nix

@@ -36,6 +36,9 @@
             DATABASE_URL = "postgresql://user:pass@localhost:5432/db";
           };
         };
+        fetch = {
+          command = "mcp-server-fetch";
+        };
         disabled-server = {
           command = "disabled-cmd";
           disabled = true;