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

pom.xml

@@ -10,7 +10,7 @@
     <groupId>io.github.git-commit-id</groupId>
     <artifactId>git-commit-id-plugin-core</artifactId>
     <packaging>jar</packaging>
-    <version>6.0.0-rc.6</version>
+    <version>6.1.0-SNAPSHOT</version>
     <name>Git Commit Id Plugin Core</name>
     <url>https://github.com/git-commit-id/git-commit-id-plugin-core</url>
 
@@ -25,7 +25,7 @@
         <url>[email protected]:git-commit-id/git-commit-id-plugin-core.git</url>
         <connection>scm:[email protected]:git-commit-id/git-commit-id-plugin-core</connection>
         <developerConnection>scm:git:[email protected]:git-commit-id/git-commit-id-plugin-core.git</developerConnection>
-        <tag>v6.0.0-rc.6</tag>
+        <tag>HEAD</tag>
     </scm>
 
     <properties>