[2.9.x] Pin sbt-paradox

[mkurz]

• [2.9.x] sbt-paradox 0.11.0 (was 0.10.7) #1395
  • parboiled needs java 17

[error] (docs / Compile / paradoxProcessor) java.lang.UnsupportedClassVersionError: org/pegdown/ParserWithDirectives has been compiled by a more recent version of the Java Runtime (class file version 61.0), this version of the Java Runtime only recognizes class file versions up to 55.0
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