Go to two-place version scheme

The major version is the upstream JDK major, and the minor is the sequential (bugfix) release from that version

Author: dmlloyd

pom.xml

@@ -6,7 +6,7 @@
 
     <groupId>io.github.dmlloyd</groupId>
     <artifactId>jdk-classfile-preview</artifactId>
-    <version>23.0.0-SNAPSHOT</version>
+    <version>23.0-SNAPSHOT</version>
 
     <name>JDK Classfile API backport (Unofficial)</name>
     <description>An unofficial backport of the JDK Classfile API to Java 17</description>