fix(opossum-reporter): Fix type error in package type field

Not sure, why this hasn't surfaced before, because there was a type
mismatch. I want to use the toString() method instead of serializing
the enum. Enum serialization is inconsistent with toString() behavior
out of the box. Custom serializer does not seem to be a maintainable
option here.

Signed-off-by: alexzurbonsen <[email protected]>

Author: alexzurbonsen

plugins/reporters/opossum/src/main/kotlin/OpossumReporter.kt

@@ -560,7 +560,7 @@ class OpossumReporter(
                 excludeFromNotice: Boolean = false
             ): OpossumSignal = OpossumSignal(
                     source = OpossumSignalSource(name = source),
-                    packageType = id?.getPurlType(),
+                    packageType = id?.getPurlType().toString(),
                     packageNamespace = id?.namespace,
                     packageName = id?.name,
                     packageVersion = id?.version,