feat(deno.jsonc): Exclude certain directories and files

This commit updates the 'deno.jsonc' file to exclude 'test_project',
'__snapshots__', and 'mod_test.ts' from being processed. This is done
to prevent unnecessary processing and to improve performance.

Author: ryoppippi

deno.jsonc

@@ -42,5 +42,10 @@
     "preprocess",
     "css",
     "import"
+  ],
+  "exclude": [
+    "test_project",
+    "__snapshots__",
+    "mod_test.ts"
   ]
 }