feat: bump node12 to node16 (#617)

Close https://github.com/peaceiris/actions-hugo/issues/611

- deps: bump node12 to node16
- deps: bump @actions/core from 1.6.0 to 1.10.0

package.json

@@ -4,8 +4,8 @@
   "description": "GitHub Actions for Hugo",
   "main": "lib/index.js",
   "engines": {
-    "node": ">=12.14.1",
-    "npm": ">=6.13.7"
+    "node": ">=16.18.0",
+    "npm": ">=8.19.0"
   },
   "scripts": {
     "all": "npm run format:check && npm run lint && npm test",
@@ -47,7 +47,7 @@
   },
   "homepage": "https://github.com/peaceiris/actions-hugo#readme",
   "dependencies": {
-    "@actions/core": "^1.6.0",
+    "@actions/core": "^1.10.0",
     "@actions/exec": "^1.1.1",
     "@actions/io": "^1.1.0",
     "@actions/tool-cache": "^1.7.2",