MINOR: Update scala version in bin scripts to 2.13.8 (#12477)

This PR updates scala versions inside `bin/scripts` (i.e., `kafka-run-class.sh`).
#12273 only modified `gradle.properties`.

Reviewers: Ismael Juma <ismael@juma.me.uk>

Signed-off-by: morsak <xorsak02@stud.fit.vutbr.cz>

bin/kafka-run-class.sh

@@ -48,7 +48,7 @@ should_include_file() {
 base_dir=$(dirname $0)/..
 
 if [ -z "$SCALA_VERSION" ]; then
-  SCALA_VERSION=2.13.6
+  SCALA_VERSION=2.13.8
   if [[ -f "$base_dir/gradle.properties" ]]; then
     SCALA_VERSION=`grep "^scalaVersion=" "$base_dir/gradle.properties" | cut -d= -f 2`
   fi

bin/windows/kafka-run-class.bat

@@ -27,7 +27,7 @@ set BASE_DIR=%CD%
 popd
 
 IF ["%SCALA_VERSION%"] EQU [""] (
-  set SCALA_VERSION=2.13.6
+  set SCALA_VERSION=2.13.8
 )
 
 IF ["%SCALA_BINARY_VERSION%"] EQU [""] (