refactor: Rename Deno main file to index.ts and update import

deno/deno.lock

@@ -0,0 +1,21 @@
+{
+  "version": "3",
+  "packages": {
+    "specifiers": {
+      "jsr:@std/assert@1": "jsr:@std/assert@1.0.11",
+      "jsr:@std/internal@^1.0.5": "jsr:@std/internal@1.0.5"
+    },
+    "jsr": {
+      "@std/assert@1.0.11": {
+        "integrity": "2461ef3c368fe88bc60e186e7744a93112f16fd110022e113a0849e94d1c83c1",
+        "dependencies": [
+          "jsr:@std/internal@^1.0.5"
+        ]
+      },
+      "@std/internal@1.0.5": {
+        "integrity": "54a546004f769c1ac9e025abd15a76b6671ddc9687e2313b67376125650dc7ba"
+      }
+    }
+  },
+  "remote": {}
+}

deno/main_test.ts

@@ -1,5 +1,5 @@
 import { assertEquals } from "@std/assert";
-import { add } from "./main.ts";
+import { add } from "./index.ts";
 
 Deno.test(function addTest() {
   assertEquals(add(2, 3), 5);