CI: added an env to enable dstester version checkout

Signed-off-by: ismail <mohammed.ismail@openairinterface.org>

ci-scripts/Jenkinsfile-Bracket-Test

@@ -205,7 +205,7 @@ pipeline {
                 [$class: 'UsernamePasswordMultiBinding', credentialsId: "${params.dsTesterGitLabRepository_Credentials}", usernameVariable: 'git_username', passwordVariable: 'git_token']
               ]) {
                 sh "git clone https://${git_username}:${git_token}@github.com/OPENAIRINTERFACE/chasseur.git . > ../git_clone.log 2>&1"
-                sh "git checkout edge >> ../git_clone.log 2>&1"
+                sh "git checkout -f " + dsTesterTag + " >> ../git_clone.log 2>&1"
                 dir ('jenkins') {
                   try {
                     sh "python3 ./dogmatix-agent.py -f ./suits/dc/amf-bracket.yaml -d true | tee ../../DS-TEST-RESULTS/dsTester_Summary.txt"