Lib: Fix ssh value for gpg.format throwing an IllegalArgumentException

Git version 2.34 and later supports signing commits and tags with SSH keys. This means gpg.format now supports "ssh" as a value.

Change-Id: Iee1e5a68a816bec149a17a73a6916d2884a54163

org.eclipse.jgit.test/tst/org/eclipse/jgit/lib/GpgConfigTest.java

diff --git a/org.eclipse.jgit.test/tst/org/eclipse/jgit/lib/GpgConfigTest.java b/org.eclipse.jgit.test/tst/org/eclipse/jgit/lib/GpgConfigTest.java
index 32f6766..5c2b190 100644
--- a/org.eclipse.jgit.test/tst/org/eclipse/jgit/lib/GpgConfigTest.java
+++ b/org.eclipse.jgit.test/tst/org/eclipse/jgit/lib/GpgConfigTest.java
@@ -96,6 +96,16 @@ public void testGetKeyFormat_x509() throws Exception {
 	}
 
 	@Test
+	public void testGetKeyFormat_ssh() throws Exception {
+		Config c = parse("" //
+				+ "[gpg]\n" //
+				+ "  format = ssh\n" //
+		);
+
+		assertEquals(GpgConfig.GpgFormat.SSH, new GpgConfig(c).getKeyFormat());
+	}
+
+	@Test
 	public void testGetSigningKey() throws Exception {
 		Config c = parse("" //
 				+ "[user]\n" //

org.eclipse.jgit/src/org/eclipse/jgit/lib/GpgConfig.java

diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/lib/GpgConfig.java b/org.eclipse.jgit/src/org/eclipse/jgit/lib/GpgConfig.java
index 427a235..4b0c079 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/lib/GpgConfig.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/lib/GpgConfig.java
@@ -24,7 +24,9 @@ public enum GpgFormat implements Config.ConfigEnum {
 		/** Value for openpgp */
 		OPENPGP("openpgp"), //$NON-NLS-1$
 		/** Value for x509 */
-		X509("x509"); //$NON-NLS-1$
+		X509("x509"), //$NON-NLS-1$
+		/** Value for ssh */
+		SSH("ssh"); //$NON-NLS-1$
 
 		private final String configValue;