chore(deps): bump ktor_version from 2.3.8 to 2.3.9 in /backend

Bumps `ktor_version` from 2.3.8 to 2.3.9.

Updates `io.ktor:ktor-client-core` from 2.3.8 to 2.3.9
- [Release notes](https://github.com/ktorio/ktor/releases)
- [Changelog](https://github.com/ktorio/ktor/blob/2.3.9/CHANGELOG.md)
- [Commits](ktorio/ktor@2.3.8...2.3.9)

Updates `io.ktor:ktor-client-apache` from 2.3.8 to 2.3.9
- [Release notes](https://github.com/ktorio/ktor/releases)
- [Changelog](https://github.com/ktorio/ktor/blob/2.3.9/CHANGELOG.md)
- [Commits](ktorio/ktor@2.3.8...2.3.9)

Updates `io.ktor:ktor-serialization-jackson` from 2.3.8 to 2.3.9
- [Release notes](https://github.com/ktorio/ktor/releases)
- [Changelog](https://github.com/ktorio/ktor/blob/2.3.9/CHANGELOG.md)
- [Commits](ktorio/ktor@2.3.8...2.3.9)

Updates `io.ktor:ktor-client-content-negotiation` from 2.3.8 to 2.3.9
- [Release notes](https://github.com/ktorio/ktor/releases)
- [Changelog](https://github.com/ktorio/ktor/blob/2.3.9/CHANGELOG.md)
- [Commits](ktorio/ktor@2.3.8...2.3.9)

---
updated-dependencies:
- dependency-name: io.ktor:ktor-client-core
  dependency-type: direct:production
  update-type: version-update:semver-patch
- dependency-name: io.ktor:ktor-client-apache
  dependency-type: direct:production
  update-type: version-update:semver-patch
- dependency-name: io.ktor:ktor-serialization-jackson
  dependency-type: direct:production
  update-type: version-update:semver-patch
- dependency-name: io.ktor:ktor-client-content-negotiation
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

backend/build.gradle

@@ -29,7 +29,7 @@ plugins {
 }
 
 ext {
-    ktor_version = "2.3.8"
+    ktor_version = "2.3.9"
 }
 
 repositories {