Bump http-graceful-shutdown from 3.1.4 to 3.1.5

Bumps [http-graceful-shutdown](https://github.com/sebhildebrandt/http-graceful-shutdown) from 3.1.4 to 3.1.5.
- [Release notes](https://github.com/sebhildebrandt/http-graceful-shutdown/releases)
- [Commits](https://github.com/sebhildebrandt/http-graceful-shutdown/commits)

---
updated-dependencies:
- dependency-name: http-graceful-shutdown
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

package.json

@@ -21,7 +21,7 @@
     "github-username-regex": "^1.0.0",
     "handlebars": "^4.7.7",
     "http-errors": "^1.8.1",
-    "http-graceful-shutdown": "^3.1.4",
+    "http-graceful-shutdown": "^3.1.5",
     "koa": "^2.13.4",
     "koa-bodyparser": "^4.3.0",
     "koa-handlebars": "^2.0.0",