[maven-release-plugin] prepare release slack-2.26

pom.xml

@@ -10,7 +10,7 @@
 
     <artifactId>slack</artifactId>
     <packaging>hpi</packaging>
-    <version>2.26-SNAPSHOT</version>
+    <version>2.26</version>
     <name>Slack Notification Plugin</name>
     <description>A Build status publisher that notifies channels on a Slack team</description>
     <url>http://wiki.jenkins-ci.org/display/JENKINS/Slack+Plugin</url>
@@ -44,7 +44,7 @@
         <connection>scm:git:ssh://[email protected]/jenkinsci/slack-plugin.git</connection>
         <developerConnection>scm:git:ssh://[email protected]/jenkinsci/slack-plugin.git</developerConnection>
         <url>https://github.com/jenkinsci/slack-plugin</url>
-        <tag>head</tag>
+        <tag>slack-2.26</tag>
     </scm>
 
     <distributionManagement>