Release 1.3.1

Signed-off-by: Szymon Janc <szymon.janc@codecoup.pl>
diff --git a/scripts/setup.py b/scripts/setup.py
index 67cca9f..0eeeba5 100644
--- a/scripts/setup.py
+++ b/scripts/setup.py
@@ -2,7 +2,7 @@
 
 setuptools.setup(
     name="imgtool",
-    version="1.3.0",
+    version="1.3.1",
     author="The MCUboot commiters",
     description=("MCUboot's image signing and key management"),
     license="Apache Software License",