Add type: commonjs package.json to cjs output

Author: dgreif

package.json

@@ -34,7 +34,7 @@
     "prebuild": "npm run clean && npm run lint && mkdir dist",
     "build": "npm run build:esm && npm run build:cjs",
     "build:esm": "tsc",
-    "build:cjs": "tsc --module commonjs --outDir dist/cjs",
+    "build:cjs": "tsc --module commonjs --outDir dist/cjs && echo '{\"type\": \"commonjs\"}' > dist/cjs/package.json",
     "clean": "rm -rf dist",
     "lint": "eslint --report-unused-disable-directives . --color --ext .js,.ts,.tsx && tsc --noEmit",
     "prepublishOnly": "npm run build",