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

pom.xml

@@ -5,7 +5,7 @@
   <groupId>com.samskivert</groupId>
   <artifactId>depot</artifactId>
   <packaging>jar</packaging>
-  <version>1.8.1</version>
+  <version>1.9-SNAPSHOT</version>
 
   <name>Depot</name>
   <description>A library for relational-database-based persistence in Java.</description>
@@ -35,7 +35,7 @@
     <connection>scm:git:git://github.com/threerings/depot.git</connection>
     <developerConnection>scm:git:git@github.com:threerings/depot.git</developerConnection>
     <url>https://github.com/threerings/depot/</url>
-    <tag>depot-1.8.1</tag>
+    <tag>HEAD</tag>
   </scm>
 
   <dependencies>