update test matrix + fix shield

.github/workflows/maven.yml

@@ -15,7 +15,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        java: ['1.8','11','12','13', '14']
+        java: ['1.8','11', '17', '21']
 
     steps:
     - uses: actions/checkout@v2

README.md

@@ -1,7 +1,7 @@
 # vatchecker: a java library for fetching information from the VIES and TIN webservice
 
 [![Maven Central](https://img.shields.io/maven-central/v/ch.digitalfondue.vatchecker/vatchecker.svg)](http://search.maven.org/#search%7Cga%7C1%7Ca%3A%22vatchecker%22)
-[![Build Status](https://img.shields.io/github/workflow/status/digitalfondue/vatchecker/Java%20CI%20with%20Maven)](https://github.com/digitalfondue/vatchecker/actions?query=workflow%3A%22Java+CI+with+Maven%22)
+[![Build Status](https://img.shields.io/github/workflow/status/digitalfondue/vatchecker/.github/workflows/maven.yml)](https://github.com/digitalfondue/vatchecker/actions?query=workflow%3A%22Java+CI+with+Maven%22)
 
 A small java client with 0 dependencies for calling:
  - the European "VAT Information Exchange System" (VIES) webservice for validating the VAT numbers. See http://ec.europa.eu/taxation_customs/vies/ .