Bump scala-xml to 1.0.6

[ghost]

at https://github.com/tpolecat/tut/blob/master/core/build.sbt#L14

ref https://gitter.im/47deg/sbt-microsites?at=59a45eaac101bc4e3a6687f8 onwards

ref 47degrees/sbt-microsites#215

[ghost]

Error msg is:

[info] Resolving org.scala-lang.modules#scala-xml_2.13.0-M1;1.0.5 ...
[warn]  module not found: org.scala-lang.modules#scala-xml_2.13.0-M1;1.0.5
[warn] ==== local: tried
[warn]   /home/alistair/.ivy2/local/org.scala-lang.modules/scala-xml_2.13.0-M1/1.0.5/ivys/ivy.xml
[warn] ==== public: tried
[warn]   https://repo1.maven.org/maven2/org/scala-lang/modules/scala-xml_2.13.0-M1/1.0.5/scala-xml_2.13.0-M1-1.0.5.pom
[warn] ==== tpolecat: tried
[warn]   http://dl.bintray.com/tpolecat/maven/org/scala-lang/modules/scala-xml_2.13.0-M1/1.0.5/scala-xml_2.13.0-M1-1.0.5.pom
[warn] ==== sonatype-releases: tried
[warn]   https://oss.sonatype.org/content/repositories/releases/org/scala-lang/modules/scala-xml_2.13.0-M1/1.0.5/scala-xml_2.13.0-M1-1.0.5.pom
[warn]  ::::::::::::::::::::::::::::::::::::::::::::::
[warn]  ::          UNRESOLVED DEPENDENCIES         ::
[warn]  ::::::::::::::::::::::::::::::::::::::::::::::
[warn]  :: org.scala-lang.modules#scala-xml_2.13.0-M1;1.0.5: not found
[warn]  ::::::::::::::::::::::::::::::::::::::::::::::
[warn] 
[warn]  Note: Unresolved dependencies path:
[warn]          org.scala-lang.modules:scala-xml_2.13.0-M1:1.0.5
[warn]            +- org.tpolecat:tut-core_2.13.0-M1:0.5.3 ((tut.TutPlugin) TutPlugin.scala#L36)
[warn]            +- com.github.typelevel:catalysts-docs_2.13.0-M1:0.0.6-SNAPSHOT ()
[trace] Stack trace suppressed: run last docs/*:update for the full output.

so for 2.13.0-M1, version 1.0.6 is needed at
https://github.com/tpolecat/tut/blob/master/core/build.sbt#L14

[ghost]

see https://oss.sonatype.org/content/repositories/releases/org/scala-lang/modules/scala-xml_2.13.0-M1/ - it's only available for 1.0.6

[tpolecat]

Aha ok. Interesting. Thanks.

[tpolecat]

Done.