Bump apksigner version to 0.4

Test: apksigner --version
Change-Id: I6815838cdc256757c4eb7db1ca79dee02691eda6
diff --git a/src/apksigner/java/com/android/apksigner/ApkSignerTool.java b/src/apksigner/java/com/android/apksigner/ApkSignerTool.java
index dbb9c64..745fe39 100644
--- a/src/apksigner/java/com/android/apksigner/ApkSignerTool.java
+++ b/src/apksigner/java/com/android/apksigner/ApkSignerTool.java
@@ -65,7 +65,7 @@
  */
 public class ApkSignerTool {
 
-    private static final String VERSION = "0.3";
+    private static final String VERSION = "0.4";
     private static final String HELP_PAGE_GENERAL = "help.txt";
     private static final String HELP_PAGE_SIGN = "help_sign.txt";
     private static final String HELP_PAGE_VERIFY = "help_verify.txt";