Bump dotnet-stryker from 4.3.0 to 4.4.1 in /src/backend

Bumps [dotnet-stryker](https://github.com/stryker-mutator/stryker-net) from 4.3.0 to 4.4.1.
- [Changelog](https://github.com/stryker-mutator/stryker-net/blob/master/CHANGELOG.md)
- [Commits](https://github.com/stryker-mutator/stryker-net/compare/[email protected]@4.4.1)

---
updated-dependencies:
- dependency-name: dotnet-stryker
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

src/backend/.config/dotnet-tools.json

@@ -24,7 +24,7 @@
       "rollForward": false
     },
     "dotnet-stryker": {
-      "version": "4.3.0",
+      "version": "4.4.1",
       "commands": [
         "dotnet-stryker"
       ],