[meta] use npmignore to autogenerate an npmignore file

Author: ljharb

.gitignore

@@ -23,3 +23,5 @@ yarn.lock
 
 coverage/
 .nyc_output/
+
+.npmignore

package.json

@@ -4,6 +4,7 @@
 	"description": "Determine if a function is an ES6 arrow function or not.",
 	"main": "index.js",
 	"scripts": {
+		"prepack": "npmignore --auto --commentLines=autogenerated",
 		"prepublishOnly": "safe-publish-latest",
 		"prepublish": "not-in-publish || npm run prepublishOnly",
 		"pretest": "npm run lint",
@@ -46,6 +47,7 @@
 		"make-arrow-function": "^1.2.0",
 		"make-async-function": "^1.0.0",
 		"make-generator-function": "^2.0.0",
+		"npmignore": "^0.3.0",
 		"nyc": "^10.3.2",
 		"safe-publish-latest": "^2.0.0",
 		"tape": "^5.6.1"
@@ -70,5 +72,10 @@
 	},
 	"engines": {
 		"node": ">= 0.4"
+	},
+	"publishConfig": {
+		"ignore": [
+			".github/workflows"
+		]
 	}
 }