Fix the 'Bundle-License'-Property in the META-INF file

According to
https://docs.osgi.org/specification/osgi.core/7.0.0/framework.module.html
the Bundle-License property should contain the license-identifier (with
the suggestion to use the SPDX-identifier: https://spdx.org/licenses/)

Author: Carl Mai

build-logic/src/main/java/org/ehcache/build/conventions/BndConvention.java

@@ -69,7 +69,7 @@ public static Action<MapProperty<String, String>> bundleDefaults(Project project
       });
       properties.put(Constants.BUNDLE_SYMBOLICNAME, project.getGroup() + "." + project.getName());
       properties.put(Constants.BUNDLE_DOCURL, "http://ehcache.org");
-      properties.put(Constants.BUNDLE_LICENSE, "LICENSE");
+      properties.put(Constants.BUNDLE_LICENSE, "Apache-2.0");
       properties.put(Constants.BUNDLE_VENDOR, "Terracotta Inc., a wholly-owned subsidiary of Software AG USA, Inc.");
       properties.put(Constants.BUNDLE_VERSION, osgiFixedVersion(project.getVersion().toString()));
       properties.put(Constants.SERVICE_COMPONENT, "OSGI-INF/*.xml");