Update plugins to use plexus-archiver 3.0.3 (minimum required for Java 9)
diff --git a/pom.xml b/pom.xml
index f7a7a81..be81839 100644
--- a/pom.xml
+++ b/pom.xml
@@ -189,6 +189,13 @@
           <groupId>org.eclipse.tycho</groupId>
           <artifactId>tycho-p2-repository-plugin</artifactId>
           <version>${tycho-version}</version>
+          <dependencies>
+            <dependency>
+              <groupId>org.codehaus.plexus</groupId>
+              <artifactId>plexus-archiver</artifactId>
+              <version>3.0.3</version>
+            </dependency>
+          </dependencies>
         </plugin>
         <plugin>
           <groupId>org.eclipse.tycho</groupId>
@@ -208,6 +215,11 @@
               <artifactId>tycho-sourceref-jgit</artifactId>
               <version>${tycho-version}</version>
             </dependency>
+            <dependency>
+              <groupId>org.codehaus.plexus</groupId>
+              <artifactId>plexus-archiver</artifactId>
+              <version>3.0.3</version>
+            </dependency>
           </dependencies>
         </plugin>
         <plugin>
@@ -222,6 +234,13 @@
               </goals>
             </execution>
           </executions>
+          <dependencies>
+            <dependency>
+              <groupId>org.codehaus.plexus</groupId>
+              <artifactId>plexus-archiver</artifactId>
+              <version>3.0.3</version>
+            </dependency>
+          </dependencies>
         </plugin>
         <plugin>
           <artifactId>maven-clean-plugin</artifactId>