chore(deps): bump @actions/core from 2.0.3 to 3.0.1 (#1746)

* chore(deps): bump @actions/core from 2.0.3 to 3.0.1

Bumps [@actions/core](https://github.com/actions/toolkit/tree/HEAD/packages/core) from 2.0.3 to 3.0.1.
- [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: 3.0.1
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>

* chore: update test mocks for @actions/core ESM

@actions/core v3 ships as an ESM module with non-configurable exports,
breaking vi.spyOn(). Switch to vi.mock('@actions/core') which
intercepts at the module loader level.

---------

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: Tom Keller <kellertk@amazon.com>

package.json

@@ -33,7 +33,7 @@
     "vitest": "^4.1.5"
   },
   "dependencies": {
-    "@actions/core": "^2.0.2",
+    "@actions/core": "^3.0.1",
     "@aws-sdk/client-sts": "^3.1038.0",
     "@smithy/node-http-handler": "^4.6.1",
     "proxy-agent": "^8.0.1"