[Tests] switch to nyc for coverage

.nycrc

@@ -0,0 +1,13 @@
+{
+	"all": true,
+	"check-coverage": false,
+	"reporter": ["text-summary", "text", "html", "json"],
+	"lines": 86,
+	"statements": 85.93,
+	"functions": 82.43,
+	"branches": 76.06,
+	"exclude": [
+		"coverage",
+		"test"
+	]
+}

package.json

@@ -27,27 +27,25 @@
   },
   "devDependencies": {
     "@ljharb/eslint-config": "^21.0.1",
-    "covert": "^1.1.1",
     "eslint": "=8.8.0",
     "in-publish": "^2.0.1",
     "npmignore": "^0.3.0",
+    "nyc": "^10.3.2",
     "safe-publish-latest": "^2.0.0",
     "tape": "^5.6.3"
   },
   "license": "MIT",
   "scripts": {
-	"prepublishOnly": "safe-publish-latest",
-	"prepublish": "not-in-publish || npm run prepublishOnly",
+    "prepublishOnly": "safe-publish-latest",
+    "prepublish": "not-in-publish || npm run prepublishOnly",
     "prepack": "npmignore --auto --commentLines=autogenerated",
     "pretest": "npm run lint",
     "test": "npm run tests-only",
-    "posttest": "npm run coverage -- --quiet",
     "preaudit": "npm install --package-lock --package-lock-only",
     "audit": "npm audit",
     "postaudit": "rm package-lock.json",
-    "tests-only": "node test",
-    "coverage": "covert test/*.js",
-    "lint": "eslint ."
+    "tests-only": "nyc tape 'test/**/*.js'",
+    "lint": "eslint --ext=js,mjs ."
   },
   "testling": {
     "files": "test/index.js",