Revert "fix: remove cache which are not in default branch (#11)"

This reverts commit 969e21a.

Author: pranc1ngpegasus

action.yml

@@ -9,5 +9,10 @@ runs:
     - shell: bash
       run: |
         gh extension install actions/gh-actions-cache
-        defaultBranch=$(gh api repos/${ github.repository } --jq '.default_branch')
-        gh actions-cache list --limit 100 | grep -v "refs/heads/${defaultBranch}" | cut -f 1 | xargs -I{} gh actions-cache delete --confirm {}
+
+        mergedPRNumbers=$(gh pr list --state merged --json number | jq .[].number)
+
+        for prNumber in $mergedPRNumbers
+        do
+          gh actions-cache list -B refs/pull/$prNumber/merge | cut -f 1 | xargs -I{} gh actions-cache delete --confirm {}
+        done