Bump dotnet-reportgenerator-globaltool in /src/backend

Bumps [dotnet-reportgenerator-globaltool](https://github.com/danielpalme/ReportGenerator) from 5.3.8 to 5.3.9.
- [Release notes](https://github.com/danielpalme/ReportGenerator/releases)
- [Commits](danielpalme/ReportGenerator@v5.3.8...v5.3.9)

---
updated-dependencies:
- dependency-name: dotnet-reportgenerator-globaltool
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

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

@@ -10,7 +10,7 @@
       "rollForward": false
     },
     "dotnet-reportgenerator-globaltool": {
-      "version": "5.3.8",
+      "version": "5.3.9",
       "commands": [
         "reportgenerator"
       ],