Bump @actions/core from 1.2.0 to 1.2.6 in /robomaker-sample-app-ci (#15)

Bumps [@actions/core](https://github.com/actions/toolkit/tree/HEAD/packages/core) from 1.2.0 to 1.2.6.
- [Release notes](https://github.com/actions/toolkit/releases)
- [Changelog](https://github.com/actions/toolkit/blob/main/packages/core/RELEASES.md)
- [Commits](https://github.com/actions/toolkit/commits/HEAD/packages/core)

Signed-off-by: dependabot[bot] <[email protected]>

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

Author: dependabot[bot]

robomaker-sample-app-ci/package-lock.json

@@ -33,7 +33,7 @@
   },
   "homepage": "https://github.com/aws-robotics/action-aws-robomaker-sample-application-ci.git#readme",
   "dependencies": {
-    "@actions/core": "^1.2.0",
+    "@actions/core": "^1.2.6",
     "@actions/exec": "^1.0.1"
   },
   "devDependencies": {