CI: updated paths in scripts

.ci_scripts/run_cppcheck.sh

 EXITCODE=0
 
 # Pattern matching on all source files
-for file in $(find $GITHUB_WORKSPACE/include $GITHUB_WORKSPACE/src $GITHUB_WORKSPACE/test -name *.h -o -name *.c)
+for file in $(find include src test -name *.h -o -name *.c)
 do
     if [[ "$file" != *"/hashmap.c" ]]
     then

.ci_scripts/run_tests.sh

 EXITCODE=0
-VALGRIND_SUPP="$GITHUB_WORKSPACE/.ci_scripts/valgrind.supp"
+VALGRIND_SUPP=".ci_scripts/valgrind.supp"
 
-for file in $GITHUB_WORKSPACE/bin/test/*
+for file in bin/test/*
 do
     if [[ $# -eq 1 && $1 == valgrind ]]
     then