Bump javalin from 5.5.0 to 5.6.1 in /reposilite-backend

Bumps `javalin` from 5.5.0 to 5.6.1.

Updates `io.javalin:javalin` from 5.5.0 to 5.6.1
- [Commits](javalin/javalin@javalin-parent-5.5.0...javalin-parent-5.6.1)

Updates `io.javalin.community.ssl:ssl-plugin` from 5.5.0 to 5.6.1
- [Release notes](https://github.com/javalin/javalin-ssl/releases)
- [Commits](javalin/javalin-ssl@5.5.0...5.6.1)

---
updated-dependencies:
- dependency-name: io.javalin:javalin
  dependency-type: direct:production
  update-type: version-update:semver-minor
- dependency-name: io.javalin.community.ssl:ssl-plugin
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

reposilite-backend/build.gradle.kts

@@ -42,7 +42,7 @@ dependencies {
     implementation("org.jetbrains.kotlin:kotlin-reflect:$kotlin")
     implementation("org.jetbrains.kotlin:kotlin-stdlib-jdk8:$kotlin")
 
-    val javalin = "5.5.0"
+    val javalin = "5.6.1"
     api("io.javalin:javalin:$javalin")
     api("io.javalin.community.ssl:ssl-plugin:$javalin")