Use eskatos/gradle-command-action instead of manually handling caching

.github/runner-files/checksum.sh

@@ -1,23 +0,0 @@
-#!/bin/bash
-RESULT_FILE=$1
-
-if [ -f $RESULT_FILE ]; then
-  rm $RESULT_FILE
-fi
-touch $RESULT_FILE
-
-checksum_file() {
-  echo $(openssl md5 $1 | awk '{print $2}')
-}
-
-FILES=()
-while read -r -d ''; do
-  FILES+=("$REPLY")
-done < <(find . -type f \( -name "build.gradle*" -o -name "Dependencies.kt" -o -name "gradle-wrapper.properties" \) -print0)
-
-# Loop through files and append MD5 to result file
-for FILE in ${FILES[@]}; do
-  echo $(checksum_file $FILE) >> $RESULT_FILE
-done
-# Now sort the file so that it is 
-sort $RESULT_FILE -o $RESULT_FILE