We (obviously) need a proper working copy to test the backports.

Switch to checking out via svn instead of from github.

* .github/workflows/detect-backport-conflicts.yml
  (steps): Remove git-stuff and add svn-stuff


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1924125 13f79535-47bb-0310-9956-ffa450edef68

Author: d-sahlberg

.github/workflows/detect-backport-conflicts.yml

@@ -43,13 +43,9 @@ jobs:
           sudo apt-get install
           subversion
           
-      - name: Use LF for Git checkout
-        run: |
-          git config --global core.autocrlf false
-          git config --global core.eol lf
-
-      - uses: actions/checkout@v4
+      - name: Checkout backport branch
+        run: svn co https://svn.apache.org/repos/asf/subversion/branches/1.14.x
 
       - name: Detect conflicting backports
-        run: ./tools/dist/detect-conflicting-backports.py
+        run: cd 1.14.x && ./tools/dist/detect-conflicting-backports.py