[meta] use npmignore to autogenerate an npmignore file

Author: ljharb

.gitignore

@@ -9,3 +9,5 @@ yarn.lock
 
 coverage
 .nyc_output
+
+.npmignore

package.json

@@ -9,6 +9,7 @@
     "test": "test"
   },
   "scripts": {
+    "prepack": "npmignore --auto --commentLines=autogenerated",
     "prepublishOnly": "safe-publish-latest",
     "prepublish": "not-in-publish || npm run prepublishOnly",
     "pretest": "npm run lint",
@@ -32,6 +33,7 @@
     "auto-changelog": "^2.4.0",
     "eslint": "=8.8.0",
     "in-publish": "^2.0.1",
+    "npmignore": "^0.3.0",
     "safe-publish-latest": "^2.0.0",
     "tape": "^5.7.1"
   },
@@ -86,5 +88,10 @@
     "commitLimit": false,
     "backfillLimit": false,
     "hideCredit": true
+  },
+  "publishConfig": {
+    "ignore": [
+      ".github/workflows"
+    ]
   }
 }