Use double quotes.

package.json

@@ -1,29 +1,31 @@
 {
-  'name': 'portfolio-v3',
-  'private': true,
-  'version': '0.0.0',
-  'type': 'module',
-  'scripts': {
-    'dev': 'vite',
-    'build': 'vite build',
-    'lint': 'eslint . --ext js,jsx --report-unused-disable-directives --max-warnings 0',
-    'preview': 'vite preview'
+  "name": "portfolio-v3",
+  "private": true,
+  "version": "0.0.0",
+  "type": "module",
+  "scripts": {
+    "dev": "vite",
+    "build": "vite build",
+    "lint": "eslint . --ext js,jsx --report-unused-disable-directives --max-warnings 0",
+    "preview": "vite preview",
+    "predeploy": "npm run build",
+    "deploy": "gh-pages -d dist"
   },
-  'dependencies': {
-    'react': '^18.2.0',
-    'react-dom': '^18.2.0',
-    'react-icons': '^5.0.1',
-    'react-router-dom': '^6.22.2'
+  "dependencies": {
+    "react": "^18.2.",
+    "react-dom": "^18.2.0",
+    "react-icons": "^5.0.1",
+    "react-router-dom": "^6.22.2"
   },
-  'devDependencies': {
-    '@types/react': '^18.2.56',
-    '@types/react-dom': '^18.2.19',
-    '@vitejs/plugin-react': '^4.2.1',
-    'eslint': '^8.56.0',
-    'eslint-plugin-react': '^7.33.2',
-    'eslint-plugin-react-hooks': '^4.6.0',
-    'eslint-plugin-react-refresh': '^0.4.5',
-    'sass': '^1.71.1',
-    'vite': '^5.1.4'
+  "devDependencies": {
+    "@types/react": "^18.2.56",
+    "@types/react-dom": "^18.2.19",
+    "@vitejs/plugin-react": "^4.2.1",
+    "eslint": "^8.56.0",
+    "eslint-plugin-react": "^7.33.2",
+    "eslint-plugin-react-hooks": "^4.6.0",
+    "eslint-plugin-react-refresh": "^0.4.5",
+    "sass": "^1.71.1",
+    "vite": "^5.1.4"
   }
 }

vite.config.js

@@ -4,4 +4,5 @@ import react from '@vitejs/plugin-react'
 // https://vitejs.dev/config/
 export default defineConfig({
   plugins: [react()],
+  base: '/portfolio-v3/',
 })