remove unbound variable

Author: Sophia Marie Terry

.github/scripts/ipa_version_check.sh

@@ -3,7 +3,7 @@ set -eou pipefail
 
 current_version=$(jq -r '.version' tools/spectral/ipa/package.json)  
 
-previous_version=$(git show origin/"${BASE_BRANCH}":tools/spectral/ipa/package.json | jq -r '.version')  
+previous_version=$(git show origin/main:tools/spectral/ipa/package.json | jq -r '.version')  
 
 if [[ -z "$previous_version" || "$previous_version" == "null" ]]; then  
   previous_version="none"