Bump org.skife.maven:really-executable-jar-maven-plugin

Bumps [org.skife.maven:really-executable-jar-maven-plugin](https://github.com/brianm/really-executable-jar-maven-plugin) from 1.5.0 to 2.1.1.
- [Commits](https://github.com/brianm/really-executable-jar-maven-plugin/commits)

---
updated-dependencies:
- dependency-name: org.skife.maven:really-executable-jar-maven-plugin
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

pom.xml

@@ -313,7 +313,7 @@
       <plugin>
         <groupId>org.skife.maven</groupId>
         <artifactId>really-executable-jar-maven-plugin</artifactId>
-        <version>1.5.0</version>
+        <version>2.1.1</version>
         <configuration>
           <inputFile>target/s3proxy-${version}-jar-with-dependencies.jar</inputFile>
           <programFile>s3proxy</programFile>