[meta] use npmignore to autogenerate an npmignore file

Author: ljharb

.gitignore

@@ -107,3 +107,5 @@ dist
 npm-shrinkwrap.json
 package-lock.json
 yarn.lock
+
+.npmignore

.npmignore

@@ -19,6 +19,7 @@
     "./package.json": "./package.json"
   },
   "scripts": {
+    "prepack": "npmignore --auto --commentLines=autogenerated",
     "prepublishOnly": "safe-publish-latest",
     "prepublish": "not-in-publish || npm run prepublishOnly",
     "pretest": "npm run lint",
@@ -63,6 +64,7 @@
     "functions-have-names": "^1.2.3",
     "has-strict-mode": "^1.0.1",
     "in-publish": "^2.0.1",
+    "npmignore": "^0.3.0",
     "nyc": "^10.3.2",
     "safe-publish-latest": "^2.0.0",
     "tape": "^5.6.1"
@@ -86,5 +88,10 @@
     "commitLimit": false,
     "backfillLimit": false,
     "hideCredit": true
+  },
+  "publishConfig": {
+    "ignore": [
+      ".github/workflows"
+    ]
   }
 }