Use C8 for coverage

package.json

@@ -22,9 +22,8 @@
     ],
     "scripts": {
         "build": "tsc && vite build",
-        "test": "vitest run",
-        "test.coverage": "nyc npm test",
-        "test.watch": "vitest",
+        "test": "vitest",
+        "test.coverage": "vitest run --coverage",
         "prepublishOnly": "npm run build --omit=dev",
         "lint": "eslint --ext .ts src",
         "predemo": "npm run build",
@@ -72,16 +71,13 @@
     },
     "homepage": "https://docx.js.org",
     "devDependencies": {
-        "@types/chai": "^4.2.15",
-        "@types/chai-as-promised": "^7.1.5",
         "@types/inquirer": "^9.0.3",
         "@types/prompt": "^1.1.1",
         "@types/unzipper": "^0.10.4",
         "@types/xml": "^1.0.8",
         "@typescript-eslint/eslint-plugin": "^5.36.1",
         "@typescript-eslint/parser": "^5.36.1",
-        "chai": "^4.3.6",
-        "chai-as-promised": "^7.1.1",
+        "@vitest/coverage-c8": "^0.32.0",
         "cspell": "^6.2.2",
         "docsify-cli": "^4.3.0",
         "eslint": "^8.23.0",
@@ -95,7 +91,6 @@
         "glob": "^9.3.0",
         "inquirer": "^9.2.7",
         "jsdom": "^22.1.0",
-        "nyc": "^15.1.0",
         "pre-commit": "^1.2.2",
         "prettier": "^2.3.1",
         "process": "^0.11.10",