Merge pull request #1598 from joto/update-catch2

Update included catch2 test framework to version 2.13.7

Author: lonvia

contrib/catch2/README.contrib

@@ -1,2 +1,2 @@
 Source: https://github.com/catchorg/Catch2
-Revision: v2.13.4
+Revision: v2.13.7

contrib/catch2/README.md

@@ -2,14 +2,14 @@
 ![catch logo](artwork/catch2-logo-small.png)
 
 [![Github Releases](https://img.shields.io/github/release/catchorg/catch2.svg)](https://github.com/catchorg/catch2/releases)
-[![Build Status](https://travis-ci.org/catchorg/Catch2.svg?branch=master)](https://travis-ci.org/catchorg/Catch2)
+[![Build Status](https://travis-ci.org/catchorg/Catch2.svg?branch=v2.x)](https://travis-ci.org/catchorg/Catch2)
 [![Build status](https://ci.appveyor.com/api/projects/status/github/catchorg/Catch2?svg=true)](https://ci.appveyor.com/project/catchorg/catch2)
-[![codecov](https://codecov.io/gh/catchorg/Catch2/branch/master/graph/badge.svg)](https://codecov.io/gh/catchorg/Catch2)
-[![Try online](https://img.shields.io/badge/try-online-blue.svg)](https://wandbox.org/permlink/HU1MkiBgFetFQJU4)
+[![codecov](https://codecov.io/gh/catchorg/Catch2/branch/v2.x/graph/badge.svg)](https://codecov.io/gh/catchorg/Catch2)
+[![Try online](https://img.shields.io/badge/try-online-blue.svg)](https://wandbox.org/permlink/6JUH8Eybx4CtvkJS)
 [![Join the chat in Discord: https://discord.gg/4CWS9zD](https://img.shields.io/badge/Discord-Chat!-brightgreen.svg)](https://discord.gg/4CWS9zD)
 
 
-<a href="https://github.com/catchorg/Catch2/releases/download/v2.11.0/catch.hpp">The latest version of the single header can be downloaded directly using this link</a>
+<a href="https://github.com/catchorg/Catch2/releases/download/v2.13.7/catch.hpp">The latest version of the single header can be downloaded directly using this link</a>
 
 ## Catch2 is released!