fix delete stacks (#79)

## Summary

- Routine Change

### Details

- fixes delete stacks to get correct pull request id

.github/scripts/delete_stacks.sh

@@ -1,16 +1,17 @@
 #!/usr/bin/env bash
 
-ACTIVE_STACKS=$(aws cloudformation list-stacks | jq -r '.StackSummaries[] | select ( .StackStatus != "DELETE_COMPLETE" ) | select( .StackName | capture("^clinical-tracker-pr-(sandbox-)?(\\d+)$") ) | .StackName ')
+ACTIVE_STACKS=$(aws cloudformation list-stacks | jq -r '.StackSummaries[] | select ( .StackStatus != "DELETE_COMPLETE" ) | select( .StackName | capture("^clinical-tracker-(sandbox-)?pr-(\\d+)$") ) | .StackName ')
 
 mapfile -t ACTIVE_STACKS_ARRAY <<< "$ACTIVE_STACKS"
 
 for i in "${ACTIVE_STACKS_ARRAY[@]}"
 do 
   echo "Checking if stack $i has open pull request"
-  PULL_REQUEST=${i//pr-/}
-  PULL_REQUEST=${PULL_REQUEST//sandbox-/}
+  PULL_REQUEST=${i//clinical-tracker-pr-/}
+  PULL_REQUEST=${PULL_REQUEST//clinical-tracker-sandbox-pr-/}
   echo "Checking pull request id ${PULL_REQUEST}"
   URL="https://api.github.com/repos/NHSDigital/electronic-prescription-service-clinical-prescription-tracker/pulls/${PULL_REQUEST}"
+
   RESPONSE=$(curl "${URL}" 2>/dev/null)
   STATE=$(echo "${RESPONSE}" | jq -r .state)
   if [ "$STATE" == "closed" ]; then