Bump org.bouncycastle:bcutil-jdk18on from 1.77 to 1.78

Bumps [org.bouncycastle:bcutil-jdk18on](https://github.com/bcgit/bc-java) from 1.77 to 1.78.
- [Changelog](https://github.com/bcgit/bc-java/blob/main/docs/releasenotes.html)
- [Commits](https://github.com/bcgit/bc-java/commits)

---
updated-dependencies:
- dependency-name: org.bouncycastle:bcutil-jdk18on
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

signature-ext/build.gradle.kts

@@ -22,7 +22,7 @@ dependencies {
     implementation(project(":packet"))
 
     // https://mvnrepository.com/artifact/org.bouncycastle/bcutil-jdk18on
-    implementation("org.bouncycastle:bcutil-jdk18on:1.77")
+    implementation("org.bouncycastle:bcutil-jdk18on:1.78")
 
     testImplementation("org.junit.jupiter:junit-jupiter-api:5.10.2")
     testRuntimeOnly("org.junit.jupiter:junit-jupiter-engine:5.10.2")