Update proguard version in test

The latest version at this moment (6.2.2) that ignores mutlirelease jar
content automatically, e.g. META-INF/versions/9 directory content.

Previous versions fail with the error
"class [META-INF/versions/9/module-info.class] unexpectedly contains class [module-info]"

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/resources/testProject/interopWithProguarded/lib/build.gradle

@@ -8,7 +8,7 @@ buildscript {
     }
     dependencies {
         classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
-        classpath 'net.sf.proguard:proguard-gradle:6.0.3'
+        classpath 'net.sf.proguard:proguard-gradle:6.2.2'
     }
 }