ci: Set dynamic fetch-depth in scans workflow (#711)

Updated the GitHub Actions scans workflow to set fetch-depth dynamically based on the number of pull request commits, improving the accuracy of fetched history for analysis.

Author: yxtay

.github/workflows/scans.yml

@@ -209,6 +209,7 @@ jobs:
         with:
           repository: ${{ github.event.pull_request.head.repo.full_name || github.repository }}
           ref: ${{ github.event.pull_request.head.sha || github.sha }}
+          fetch-depth: (${{ github.event.pull_request.commits || 2 }} + 1)
 
       - id: megalinter
         # You can override MegaLinter flavor used to have faster performances