[meta] use npmignore to autogenerate an npmignore file

Author: ljharb

.gitignore

@@ -6,3 +6,5 @@ node_modules
 npm-shrinkwrap.json
 package-lock.json
 yarn.lock
+
+.npmignore

package.json

@@ -13,6 +13,7 @@
 		"aud": "^2.0.1",
 		"eslint": "=8.8.0",
 		"in-publish": "^2.0.1",
+		"npmignore": "^0.3.0",
 		"safe-publish-latest": "^2.0.0",
 		"tape": "^5.6.1"
 	},
@@ -30,12 +31,18 @@
 		"url": "http://github.com/substack/node-shell-quote.git"
 	},
 	"scripts": {
+		"prepack": "npmignore --auto --commentLines=autogenerated",
 		"prepublish": "not-in-publish || npm run prepublishOnly",
 		"prepublishOnly": "safe-publish-latest",
 		"lint": "eslint --ext=js,mjs .",
 		"pretest": "npm run lint",
 		"tests-only": "tape 'test/**/*.js'",
 		"test": "npm run tests-only",
 		"posttest": "aud --production"
+	},
+	"publishConfig": {
+		"ignore": [
+			".github/workflows"
+		]
 	}
 }