fix(PurlExtensions): Add DirectoryProvenance

Functions accepting a `KnownProvenance` often only
handle the two explicit cases of `Artifact` or
`RepositoryProvenance`.
Add `DirectoryProvenance` cases to conditional `when`s.

Signed-off-by: Jens Keim <[email protected]>

Author: pepper-jk

model/src/main/kotlin/utils/PurlExtensions.kt

@@ -22,6 +22,7 @@ package org.ossreviewtoolkit.model.utils
 import java.net.URLDecoder
 
 import org.ossreviewtoolkit.model.ArtifactProvenance
+import org.ossreviewtoolkit.model.DirectoryProvenance
 import org.ossreviewtoolkit.model.Hash
 import org.ossreviewtoolkit.model.Identifier
 import org.ossreviewtoolkit.model.Package
@@ -101,6 +102,8 @@ fun Provenance.toPurlExtras(): PurlExtras =
             )
         }
 
+        is DirectoryProvenance -> PurlExtras()
+
         is UnknownProvenance -> PurlExtras()
     }