Try and get linux tests running again

Author: stevencl840

.github/workflows/ci.yml

@@ -68,7 +68,7 @@ jobs:
         run: dotnet test LibGit2Sharp.sln --configuration Release --framework ${{ matrix.tfm }} --logger "GitHubActions" /p:ExtraDefine=LEAKS_IDENTIFYING
   test-linux:
     name: Test / ${{ matrix.distro }} / ${{ matrix.arch }} / ${{ matrix.tfm }}
-    runs-on: ${{ matrix.runnerImage }}
+    runs-on: ${{ matrix.arch == 'amd64' && 'ubuntu-24.04' || 'ubuntu-24.04-arm' }}
     strategy:
       matrix:
         arch: [ amd64, arm64 ]