pom.xml: Fix bundling of sshd-core.jar, update git dependency

git 2.0 has problematic dependencies that makes the hpi plugin bundle
sshd-core.jar into the plugin.

Update git dependency to 3.0.0. That fixes the bundling issue.

The fix was suggested by Jesse Glick in JENKINS-53957

pom.xml

@@ -90,7 +90,7 @@
         <dependency>
             <groupId>org.jenkins-ci.plugins</groupId>
             <artifactId>git</artifactId>
-            <version>2.0</version>
+            <version>3.0.0</version>
             <type>jar</type>
         </dependency>
         <dependency>