Bump org.bouncycastle:bcprov-jdk18on from 1.75 to 1.78 in /plugin-sftp

Bumps [org.bouncycastle:bcprov-jdk18on](https://github.com/bcgit/bc-java) from 1.75 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:bcprov-jdk18on
  dependency-type: direct:production
...

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

plugin-sftp/pom.xml

@@ -31,7 +31,7 @@
     <dependency>
       <groupId>org.bouncycastle</groupId>
       <artifactId>bcprov-jdk18on</artifactId>
-      <version>1.75</version>
+      <version>1.78</version>
     </dependency>
     <dependency>
       <groupId>org.bouncycastle</groupId>