Require Java 8 and bump version to 4.3.0-SNAPSHOT

Several dependencies are now build using Java 8.
Newer version of Plexus IO are build with Java 8,
and more importantly the version we use for
Common Compress requires Java 8 as well.
So essentially you need Java 8 to run Plexus Archiver anyway.

Author: plamentotev

pom.xml

@@ -10,7 +10,7 @@
   </parent>
 
   <artifactId>plexus-archiver</artifactId>
-  <version>4.2.8-SNAPSHOT</version>
+  <version>4.3.0-SNAPSHOT</version>
   <name>Plexus Archiver Component</name>
 
   <scm>
@@ -31,7 +31,7 @@
   </distributionManagement>
 
   <properties>
-    <javaVersion>7</javaVersion>
+    <javaVersion>8</javaVersion>
     <project.build.outputTimestamp>2022-01-02T11:13:08Z</project.build.outputTimestamp>
   </properties>