chore: Add Vitest configuration file for testing setup

Author: taj54

package.json

@@ -1,12 +1,12 @@
 {
   "name": "universal-version-bump",
   "displayName": "Universal Version Bump",
-  "version": "0.6.0",
+  "version": "0.6.2",
   "description": "A GitHub Action to automatically bump versions across any app (Node, Python, PHP, Docker, etc.)",
   "main": "dist/index.js",
   "scripts": {
     "build": "pnpm exec ts-node scripts/build.ts",
-    "test": "echo \"No tests yet\"",
+    "test": "vitest --config vitest.config.mts run",
     "lint": "eslint . --ext .ts",
     "format": "prettier --write .",
     "prepare": "pnpm lint --fix && pnpm format && pnpm build "
@@ -38,15 +38,17 @@
   "devDependencies": {
     "@types/node": "^24.3.0",
     "@types/semver": "^7.7.0",
-    "@vercel/ncc": "^0.38.3",
-    "ts-node": "^10.9.2",
-    "typescript": "^5.9.2",
-    "yaml": "^2.8.1",
-    "eslint": "^8.57.0",
-    "prettier": "^3.3.3",
     "@typescript-eslint/eslint-plugin": "^7.18.0",
     "@typescript-eslint/parser": "^7.18.0",
+    "@vercel/ncc": "^0.38.3",
+    "@vitest/coverage-v8": "^3.2.4",
+    "eslint": "^8.57.0",
     "eslint-config-prettier": "^9.1.0",
-    "eslint-plugin-prettier": "^5.2.1"
+    "eslint-plugin-prettier": "^5.2.1",
+    "prettier": "^3.3.3",
+    "ts-node": "^10.9.2",
+    "typescript": "^5.9.2",
+    "vitest": "^3.2.4",
+    "yaml": "^2.8.1"
   }
 }