fix: upgrade @actions/core from 1.2.3 to 1.2.4

Snyk has created this PR to upgrade @actions/core from 1.2.3 to 1.2.4.

See this package in NPM:
https://www.npmjs.com/package/@actions/core

See this project in Snyk:
https://app.snyk.io/org/nick-invision/project/b960b937-66a3-4aae-9cb2-321f49c8750b?utm_source=github&utm_medium=upgrade-pr

package.json

@@ -17,7 +17,7 @@
   },
   "homepage": "https://github.com/nick-invision/retry#readme",
   "dependencies": {
-    "@actions/core": "^1.2.3",
+    "@actions/core": "^1.2.4",
     "milliseconds": "^1.0.3",
     "tree-kill": "^1.2.2"
   },