Remove commonjs specification

The new tsconfig for node18 requires `module` to be a valid value for
the specified `moduleResolution`.  Our override resulted in a conflict.

The `Node16` module setting *allows* esm exports.  This is a bit of
a moot point for that particular config since the whole point is that it
is a configuration for common JS.  Nevertheless, it feels better to not
override if we don't need to override, and the default behavior still
exports CJS.

tsconfig.node.json

@@ -1,7 +1,6 @@
 {
   "extends": "@tsconfig/node18/tsconfig.json",
   "compilerOptions": {
-    "module": "commonjs",
     "outDir": "dist/cjs",
     "declaration": true,
     "allowSyntheticDefaultImports": true