CI: Fix prune_cache workflow to correctly delete PR-scoped caches on close (#10)

* Fix prune_cache.yaml: add workflow_dispatch input for PR number

Agent-Logs-Url: https://github.com/hansec/OpenFUSIONToolkit/sessions/9aca4978-aa09-4763-b5b3-ac382a04bba8
Agent-Logs-Url: https://github.com/hansec/OpenFUSIONToolkit/sessions/c36aa2f4-3936-423c-9102-366e4d4dea36

Co-authored-by: hansec <821577+hansec@users.noreply.github.com>

Author: Copilot

.github/workflows/prune_cache.yaml

@@ -4,6 +4,11 @@ on:
     types:
       - closed
   workflow_dispatch:
+    inputs:
+      pr_number:
+        description: 'Pull request number to clean up caches for'
+        required: true
+        type: string
 
 jobs:
   cleanup:
@@ -21,6 +26,8 @@ jobs:
         run: |
           gh extension install actions/gh-actions-cache
 
+          BRANCH="refs/pull/${PR_NUMBER}/merge"
+
           echo "Fetching list of cache key"
           cacheKeysForPR=$(gh actions-cache list -R $REPO -B $BRANCH -L 100 | cut -f 1 )
 
@@ -35,4 +42,4 @@ jobs:
         env:
           GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
           REPO: ${{ github.repository }}
-          BRANCH: refs/pull/${{ github.event.pull_request.number }}/merge
+          PR_NUMBER: ${{ github.event.pull_request.number || inputs.pr_number }}