Fix compatibility-version-numbering - skip über jar

`sbt-version-policy` kept on deciding that every release (eg
https://github.com/guardian/play-secret-rotation/releases/tag/v6.0.0 )
needed a 'MAJOR' version bump, even when there were no changes between
releases:

v5.0.0...v6.0.0

This is due to our submodule `aws-parameterstore-lambda` being released
as an über jar (with `sbt-assembly`) and the issue
scalacenter/sbt-version-policy#190 .

I think setting `versionPolicyAssessCompatibility / skip := true` may
well be enough to fix the issue, though only if
`fromAggregatedAssessedCompatibilityWithLatestRelease()` respects it-
lets see if it will!

aws-parameterstore/lambda/build.sbt

@@ -1,6 +1,9 @@
 // replace the conventional main artifact with an uber-jar
 addArtifact(Compile / packageBin / artifact, assembly)
 
+// see https://github.com/scalacenter/sbt-version-policy/issues/190
+versionPolicyAssessCompatibility / skip := true
+
 assembly / assemblyMergeStrategy := {
   {
     case PathList("META-INF", _ @ _*) => MergeStrategy.discard