Switch to using xrootd.org debian builds

We now depend on XRootD 5.7.0 or later -- that means we'll need
upstream builds.

.github/workflows/test.yml

@@ -19,8 +19,8 @@ jobs:
   build:
     strategy:
       matrix:
-        external-gtest: [ YES, NO ]
-        os: [ ubuntu-latest, ubuntu-22.04 ]
+        external-gtest: [ YES ]
+        os: [ ubuntu-24.04 ]
 
     runs-on: ${{ matrix.os }}
     name: Build with external_gtest=${{ matrix.external-gtest }} on ${{ matrix.os }}
@@ -31,6 +31,8 @@ jobs:
         submodules: recursive
     - name: install deps
       run: |
+        sudo curl -L https://xrootd.web.cern.ch/repo/RPM-GPG-KEY.txt -o /etc/apt/trusted.gpg.d/xrootd.asc
+        sudo /bin/sh -c 'echo "deb https://xrootd.web.cern.ch/ubuntu noble stable" >> /etc/apt/sources.list.d/xrootd.list'
         sudo apt update && sudo apt-get install -y cmake libcurl4-openssl-dev libcurl4 pkg-config libssl-dev xrootd-server libxrootd-dev libxrootd-server-dev libgtest-dev
 
     - name: Create Build Environment