Update scala version (2.13.18) (#899)

Author: jcp19

build.sbt

@@ -7,7 +7,7 @@
 // Settings common to Silver and backends
 // Compilation settings
 
-ThisBuild / scalaVersion := "2.13.10"
+ThisBuild / scalaVersion := "2.13.18"
 ThisBuild / scalacOptions ++= Seq(
   "-encoding", "UTF-8",               // Enforce UTF-8, instead of relying on properly set locales
   "-deprecation",                     // Warn when using deprecated language features
@@ -64,3 +64,4 @@ lazy val silver = (project in file("."))
     assembly / assemblyJarName := "silver.jar",
     assembly / test := {},
   )
+