ConfigTest: Create Git instance in try-with-resource

Change-Id: Ie65c69e0f1aed95bcdf68ebd68d21b3e2590b41c
Signed-off-by: David Pursehouse <david.pursehouse@sonymobile.com>

org.eclipse.jgit.pgm.test/tst/org/eclipse/jgit/pgm/ConfigTest.java

@@ -60,7 +60,9 @@ public class ConfigTest extends CLIRepositoryTestCase {
 	@Before
 	public void setUp() throws Exception {
 		super.setUp();
-		new Git(db).commit().setMessage("initial commit").call();
+		try (Git git = new Git(db)) {
+			git.commit().setMessage("initial commit").call();
+		}
 	}
 
 	@Test