update to "scalac -source 3.3" (from 3.1);
enforce rebuild of Isabelle/ML and Isabelle/Scala, e.g. for session HOL-Codegenerator_Test;

--- a/etc/settings	Tue Aug 29 21:54:35 2023 +0200
+++ b/etc/settings	Wed Aug 30 21:03:30 2023 +0200
@@ -17,7 +17,7 @@
 ISABELLE_TOOL_JAVA_OPTIONS="-Djava.awt.headless=true -Xms512m -Xmx4g -Xss16m"
 
 ISABELLE_JAVAC_OPTIONS="-encoding UTF-8 -Xlint:-options -deprecation -source 17 -target 17"
-ISABELLE_SCALAC_OPTIONS="-encoding UTF-8 -feature -java-output-version 17 -source 3.1 -old-syntax -no-indent -color never -pagewidth 78 -J-Xms512m -J-Xmx4g -J-Xss16m"
+ISABELLE_SCALAC_OPTIONS="-encoding UTF-8 -feature -java-output-version 17 -source 3.3 -old-syntax -no-indent -color never -pagewidth 78 -J-Xms512m -J-Xmx4g -J-Xss16m"
 
 ISABELLE_SCALA_JAR="$ISABELLE_HOME/lib/classes/isabelle.jar"
 

--- a/src/Pure/ROOT.ML	Tue Aug 29 21:54:35 2023 +0200
+++ b/src/Pure/ROOT.ML	Wed Aug 30 21:03:30 2023 +0200
@@ -370,3 +370,4 @@
 ML_file "Tools/jedit.ML";
 ML_file "Tools/ghc.ML";
 ML_file "Tools/generated_files.ML";
+

--- a/src/Pure/ROOT.scala	Tue Aug 29 21:54:35 2023 +0200
+++ b/src/Pure/ROOT.scala	Wed Aug 30 21:03:30 2023 +0200
@@ -29,4 +29,3 @@
   def if_proper[A](x: Iterable[A], body: => String): String = Library.if_proper(x, body)
   def if_proper(b: Boolean, body: => String): String = Library.if_proper(b, body)
 }
-