[fix] Deployment handles dependency elements properly

When handling dependency elements in package descriptor files
the package version attribute was checked in order to determine if
a specific dependency version was pinned for this dependency.

Now that the DOM implementation will always return an empty string
instead of null for unset attributes this now means that

1. the package version is set (otherwise the package would not install)
2. the version variable for each dependency will be non-null because
  the package version is set. The type will then vary on the attribute
  value - this would have been null in the past and is now an empty
  string which changes the resulting DependemcyVersion subtype.

Author: line-o

exist-core/src/main/java/org/exist/repo/Deployment.java

@@ -207,7 +207,7 @@ public Optional<String> installAndDeploy(final DBBroker broker, final Txn transa
                         version = new PackageLoader.Version(semVer, true);
                     } else if (!semVerMax.isEmpty() || !semVerMin.isEmpty()) {
                         version = new PackageLoader.Version(semVerMin.isEmpty() ? null: semVerMin, semVerMax.isEmpty() ? null: semVerMax);
-                    } else if (!pkgVersion.isEmpty()) {
+                    } else if (!versionStr.isEmpty()) {
                         version = new PackageLoader.Version(versionStr, false);
                     }