Merge vk-gl-cts/vulkan-cts-1.2.7 into vk-gl-cts/vulkan-cts-1.2.8

Change-Id: Id224a630047cd512b36da121961684a9350ff731
diff --git a/external/fetch_sources.py b/external/fetch_sources.py
index 8e72345..ed85168 100644
--- a/external/fetch_sources.py
+++ b/external/fetch_sources.py
@@ -299,9 +299,9 @@
 
 PACKAGES = [
 	SourcePackage(
-		"http://zlib.net/zlib-1.2.12.tar.gz",
-		"zlib-1.2.12.tar.gz",
-		"91844808532e5ce316b3c010929493c0244f3d37593afd6de04f71821d5136d9",
+		"http://zlib.net/fossils/zlib-1.2.13.tar.gz",
+		"zlib-1.2.13.tar.gz",
+		"b3a24de97a8fdbc835b9833169501030b8977031bcb54b3b3ac13740f846ab30",
 		"zlib"),
 	SourcePackage(
 		"http://prdownloads.sourceforge.net/libpng/libpng-1.6.27.tar.gz",