Bump @types/jest from 26.0.15 to 26.0.21

Bumps [@types/jest](https://github.com/DefinitelyTyped/DefinitelyTyped/tree/HEAD/types/jest) from 26.0.15 to 26.0.21.
- [Release notes](https://github.com/DefinitelyTyped/DefinitelyTyped/releases)
- [Commits](https://github.com/DefinitelyTyped/DefinitelyTyped/commits/HEAD/types/jest)

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

package.json

@@ -28,7 +28,7 @@
     "@actions/core": "^1.2.6"
   },
   "devDependencies": {
-    "@types/jest": "^26.0.15",
+    "@types/jest": "^26.0.21",
     "@types/node": "^14.14.35",
     "@typescript-eslint/parser": "^4.19.0",
     "@vercel/ncc": "^0.27.0",