feat!: switch to ESM only (#48)

Switches to ESM only now that `require(esm)` is available in all LTS
other than the soon-to-disappear 18.x.

---------

Co-authored-by: Vladimir Sheremet <[email protected]>

Author: 43081j

package.json

@@ -21,17 +21,11 @@
   ],
   "exports": {
     ".": {
-      "import": {
-        "types": "./dist/index.d.ts",
-        "default": "./dist/index.js"
-      },
-      "require": {
-        "types": "./dist/index.d.cts",
-        "default": "./dist/index.cjs"
-      }
+      "types": "./dist/index.d.ts",
+      "default": "./dist/index.js"
     }
   },
-  "main": "./dist/index.cjs",
+  "main": "./dist/index.js",
   "module": "./dist/index.js",
   "types": "./dist/index.d.ts",
   "files": [