create buildspecs for io.wcm releases

[hboutemy]

here are some POMs in Central Repository that should be easy given existing io.wcm content, for example https://github.com/jvm-repo-rebuild/reproducible-central/blob/master/content/io/wcm/wcm/wcm-ui-granite-1.7.2.buildspec

it's just cumbersome to extract buildnumberand timestamp data for each release buildspec

then help is welcome:
https://repo.maven.apache.org/maven2/io/wcm/io.wcm.sling.models/1.6.0/io.wcm.sling.models-1.6.0.pom
https://repo.maven.apache.org/maven2/io/wcm/io.wcm.caconfig.extensions/1.8.0/io.wcm.caconfig.extensions-1.8.0.pom
https://repo.maven.apache.org/maven2/io/wcm/io.wcm.testing.wcm-io-mock.wcm/1.1.0/io.wcm.testing.wcm-io-mock.wcm-1.1.0.pom
https://repo.maven.apache.org/maven2/io/wcm/io.wcm.handler.commons/1.4.0/io.wcm.handler.commons-1.4.0.pom
https://repo.maven.apache.org/maven2/io/wcm/io.wcm.testing.wcm-io-mock.handler/1.4.0/io.wcm.testing.wcm-io-mock.handler-1.4.0.pom
https://repo.maven.apache.org/maven2/io/wcm/io.wcm.dam.asset-service/1.4.0/io.wcm.dam.asset-service-1.4.0.pom
https://repo.maven.apache.org/maven2/io/wcm/io.wcm.sling.commons/1.4.0/io.wcm.sling.commons-1.4.0.pom
https://repo.maven.apache.org/maven2/io/wcm/io.wcm.wcm.core.components.parent/1.7.0-2.13.0/io.wcm.wcm.core.components.parent-1.7.0-2.13.0.pom
https://repo.maven.apache.org/maven2/io/wcm/io.wcm.testing.wcm-io-mock.sling/1.1.0/io.wcm.testing.wcm-io-mock.sling-1.1.0.pom
https://repo.maven.apache.org/maven2/io/wcm/io.wcm.testing.wcm-io-mock.caconfig/1.1.0/io.wcm.testing.wcm-io-mock.caconfig-1.1.0.pom
https://repo.maven.apache.org/maven2/io/wcm/io.wcm.caconfig.editor/1.8.0/io.wcm.caconfig.editor-1.8.0.pom
https://repo.maven.apache.org/maven2/io/wcm/io.wcm.wcm.ui.extjs/1.1.0/io.wcm.wcm.ui.extjs-1.1.0.pom
https://repo.maven.apache.org/maven2/io/wcm/io.wcm.handler.url/1.5.0/io.wcm.handler.url-1.5.0.pom
https://repo.maven.apache.org/maven2/io/wcm/io.wcm.testing.aem-mock.parent/3.2.0/io.wcm.testing.aem-mock.parent-3.2.0.pom
https://repo.maven.apache.org/maven2/org/apache/sling/org.apache.sling.api/2.23.0/org.apache.sling.api-2.23.0.pom
https://repo.maven.apache.org/maven2/io/wcm/maven/plugins/nodejs-maven-plugin/3.0.4/nodejs-maven-plugin-3.0.4.pom
https://repo.maven.apache.org/maven2/io/wcm/caravan/io.wcm.caravan.commons.httpasyncclient/1.4.0/io.wcm.caravan.commons.httpasyncclient-1.4.0.pom
https://repo.maven.apache.org/maven2/io/wcm/caravan/io.wcm.caravan.commons.httpclient/1.4.0/io.wcm.caravan.commons.httpclient-1.4.0.pom

looking at source code repositories, it seems the updates are required because of the way gitflow-maven-plugin is used: perhaps we can improve that process to avoid the need for buildnumberand timestamp?