build(deps): bump @actions/core from 1.11.1 to 2.0.0 (#243)

Bumps [@actions/core](https://github.com/actions/toolkit/tree/HEAD/packages/core) from 1.11.1 to 2.0.0.
- [Changelog](https://github.com/actions/toolkit/blob/main/packages/core/RELEASES.md)
- [Commits](https://github.com/actions/toolkit/commits/HEAD/packages/core)

---
updated-dependencies:
- dependency-name: "@actions/core"
  dependency-version: 2.0.0
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

package.json

@@ -2,7 +2,7 @@
   "name": "action-send-mail",
   "main": "main.js",
   "dependencies": {
-    "@actions/core": "^1.11.1",
+    "@actions/core": "^2.0.0",
     "@actions/glob": "^0.5.0",
     "nodemailer": "^7.0.10",
     "showdown": "^1.9.1"