Merge pull request #2959 from nlohmann/issue2938

Update Travis badge

README.md

@@ -1,6 +1,6 @@
 [![JSON for Modern C++](https://raw.githubusercontent.com/nlohmann/json/master/doc/json.gif)](https://github.com/nlohmann/json/releases)
 
-[![Build Status](https://travis-ci.org/nlohmann/json.svg?branch=master)](https://travis-ci.org/nlohmann/json)
+[![Build Status](https://app.travis-ci.com/nlohmann/json.svg?branch=develop)](https://app.travis-ci.com/nlohmann/json)
 [![Build Status](https://ci.appveyor.com/api/projects/status/1acb366xfyg3qybk/branch/develop?svg=true)](https://ci.appveyor.com/project/nlohmann/json)
 [![Ubuntu](https://github.com/nlohmann/json/workflows/Ubuntu/badge.svg)](https://github.com/nlohmann/json/actions?query=workflow%3AUbuntu)
 [![macOS](https://github.com/nlohmann/json/workflows/macOS/badge.svg)](https://github.com/nlohmann/json/actions?query=workflow%3AmacOS)