[Build] Switch badges to GH actions (TouK#1383)

.github/workflows/pr.yml

@@ -1,4 +1,4 @@
-name: "Build and Test"
+name: CI
 on:
   pull_request:
     branches:

README.md

@@ -1,6 +1,6 @@
 [![Maven Central](https://maven-badges.herokuapp.com/maven-central/pl.touk.nussknacker/nussknacker-ui_2.11/badge.svg)](https://maven-badges.herokuapp.com/maven-central/pl.touk.nussknacker/nussknacker-ui_2.11)
-[![Build Status](https://travis-ci.org/TouK/nussknacker.svg?branch=master)](https://travis-ci.org/TouK/nussknacker)
-[![Coverage Status](https://coveralls.io/repos/github/TouK/nussknacker/badge.svg?branch=master)](https://coveralls.io/github/TouK/nussknacker?branch=master)
+[![Build status](https://github.com/touk/nussknacker/workflows/CI/badge.svg)](https://github.com/touk/nussknacker/actions?query=workflow%3A%22CI%22)
+[![Coverage Status](https://coveralls.io/repos/github/TouK/nussknacker/badge.svg?branch=staging)](https://coveralls.io/github/TouK/nussknacker?branch=staging)
 [![Join the chat at https://gitter.im/TouK/nussknacker](https://badges.gitter.im/TouK/nussknacker.svg)](https://gitter.im/TouK/nussknacker?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge)
 [![Artifact HUB](https://img.shields.io/endpoint?url=https://artifacthub.io/badge/repository/touk)](https://artifacthub.io/packages/search?repo=touk)