Update unfiltered to 0.12.0

[RustedBones]

Loading sbt-site in recent sbt ecosystem fails with

[error] java.lang.RuntimeException: found version conflict(s) in library dependencies; some are suspected to be binary incompatible:
[error] 
[error]         * org.scala-lang.modules:scala-xml_2.12:2.2.0 (early-semver) is selected over 1.3.0
[error]             +- org.scoverage:scalac-scoverage-reporter_2.12:2.1.0 (depends on 2.2.0)
[error]             +- ws.unfiltered:unfiltered_2.12:0.10.4               (depends on 1.3.0)

Most of new sbt plugins expect to run with scala-xml v2 but sbt-site transitively pulls v1.

Update unfiltered to newer version, depending on scala-xml v2

sbt:sbt-site> whatDependsOn org.scala-lang.modules scala-xml_2.12
[info] org.scala-lang.modules:scala-xml_2.12:2.1.0 [S]
[info]   +-ws.unfiltered:unfiltered_2.12:0.12.0 [S]
[info]     +-ws.unfiltered:unfiltered-directives_2.12:0.12.0 [S]
[info]     | +-com.github.sbt:sbt-site:1.6.0+1-9ff99472+20240325-1004-SNAPSHOT
[info]     | 
[info]     +-ws.unfiltered:unfiltered-filter_2.12:0.12.0 [S]
[info]       +-com.github.sbt:sbt-site:1.6.0+1-9ff99472+20240325-1004-SNAPSHOT

[lightbend-cla-validator]

Hi @RustedBones,

Thank you for your contribution! We really value the time you've taken to put this together.

We see that you have signed the Lightbend Contributors License Agreement before, however, the CLA has changed since you last signed it.
Please review the new CLA and sign it before we proceed with reviewing this pull request:

http://www.lightbend.com/contribute/cla

[ennru]

Manually verified CLA, all good. Thank you!

[ennru]

LGTM.