[maven-release-plugin] prepare for next development iteration

pom.xml

@@ -5,7 +5,7 @@
     <groupId>eu.dnetlib.dhp</groupId>
     <artifactId>dhp-schemas</artifactId>
     <packaging>jar</packaging>
-    <version>2.7.19</version>
+    <version>2.7.20-SNAPSHOT</version>
 
     <licenses>
         <license>
@@ -32,7 +32,7 @@
         <connection>scm:git:gitea@code-repo.d4science.org:D-Net/dhp-schemas.git</connection>
         <developerConnection>scm:git:gitea@code-repo.d4science.org:D-Net/dhp-schemas.git</developerConnection>
         <url>https://code-repo.d4science.org/D-Net/dhp-schemas/</url>
-        <tag>dhp-schemas-2.7.19</tag>
+        <tag>dhp-schemas-2.6.13</tag>
     </scm>
 
     <description>This module contains common schema classes meant to be used across the dnet-hadoop submodules</description>