SCANMAVEN-242 update readme quality gate badge, because project key has changed (#274)

Author: erwan-serandour

README.md

@@ -1,6 +1,6 @@
 # SonarQube Scanner for Maven
 
-[![Build Status](https://api.cirrus-ci.com/github/SonarSource/sonar-scanner-maven.svg)](https://cirrus-ci.com/github/SonarSource/sonar-scanner-maven) [![Quality Gate Status](https://next.sonarqube.com/sonarqube/api/project_badges/measure?project=org.sonarsource.scanner.maven%3Asonar-maven-plugin&metric=alert_status)](https://next.sonarqube.com/sonarqube/dashboard?id=org.sonarsource.scanner.maven%3Asonar-maven-plugin)
+[![Build Status](https://api.cirrus-ci.com/github/SonarSource/sonar-scanner-maven.svg)](https://cirrus-ci.com/github/SonarSource/sonar-scanner-maven) [![Quality Gate Status](https://next.sonarqube.com/sonarqube/api/project_badges/measure?project=org.sonarsource.scanner.maven%3Asonar-scanner-maven&metric=alert_status)](https://next.sonarqube.com/sonarqube/dashboard?id=org.sonarsource.scanner.maven%3Asonar-scanner-maven)
 
 Sonar's [Clean Code solutions](https://www.sonarsource.com/solutions/clean-code/?utm_medium=referral&utm_source=github&utm_campaign=clean-code&utm_content=sonar-scanner-maven) help developers deliver high-quality, efficient code standards that benefit the entire team or organization.