fix: escape single quotes

jenkins/Jenkinsfile

@@ -61,8 +61,8 @@ pipeline {
       sleep 2
       sh 'docker images | grep -E "ecentrics/concordia.+tests" | tr -s \' \' | cut -d \' \' -f 3 | xargs --no-run-if-empty docker rmi -f || true'
 
-      sh '''docker images | tr -s ' ' | grep -E 'ecentrics/concordia.+staging-b' | sed -r 's/(v.*-staging-b)([0-9]*)/\1\2 \2/g' | awk '{ if (\$3 < ($BUILD_NUMBER - 2)) print \$1\":\"\$2}' | xargs --no-run-if-empty docker rmi -f || true'''
+      sh '''docker images | tr -s \' \' | grep -E \'ecentrics/concordia.+staging-b\' | sed -r \'s/(v.*-staging-b)([0-9]*)/\1\2 \2/g\' | awk \'{ if (\$3 < ($BUILD_NUMBER - 2)) print \$1\":\"\$2}\' | xargs --no-run-if-empty docker rmi -f || true'''
-      sh '''docker images | tr -s ' ' | grep -E 'ecentrics/concordia.+production-b' | sed -r 's/(v.*-production-b)([0-9]*)/\1\2 \2/g' | awk '{ if (\$3 < ($BUILD_NUMBER - 2)) print \$1\":\"\$2}' | xargs --no-run-if-empty docker rmi -f || true'''
+      sh '''docker images | tr -s \' \' | grep -E \'ecentrics/concordia.+production-b\' | sed -r \'s/(v.*-production-b)([0-9]*)/\1\2 \2/g\' | awk \'{ if (\$3 < ($BUILD_NUMBER - 2)) print \$1\":\"\$2}\' | xargs --no-run-if-empty docker rmi -f || true'''
 
       sh 'docker system prune -f'
       sh 'rm -rf reports'