Bump org.apache.sshd:sshd-core from 2.14.0 to 2.15.0 (#897)

Bumps [org.apache.sshd:sshd-core](https://github.com/apache/mina-sshd) from 2.14.0 to 2.15.0.
- [Release notes](https://github.com/apache/mina-sshd/releases)
- [Changelog](https://github.com/apache/mina-sshd/blob/master/CHANGES.md)
- [Commits](apache/mina-sshd@sshd-2.14.0...sshd-2.15.0)

---
updated-dependencies:
- dependency-name: org.apache.sshd:sshd-core
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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Author: dependabot[bot]

build.gradle.kts

@@ -78,7 +78,7 @@ dependencies {
     testImplementation("org.spockframework:spock-junit4:2.3-groovy-3.0")
     testImplementation("cglib:cglib-nodep:3.3.0")
     testImplementation("org.objenesis:objenesis:3.4")
-    testImplementation("org.apache.sshd:sshd-core:2.14.0")
+    testImplementation("org.apache.sshd:sshd-core:2.15.0")
     testImplementation("org.apache.sshd:sshd-git:2.15.0")
     testImplementation("com.github.stefanbirkner:system-rules:1.19.0")
     testImplementation(gradleTestKit())