GHA/checksrc: switch xmllint job to Linux (from macOS)

macOS was chosen because xmllint comes preinstalled, saving the prereq
install step. But, macOS's xmllint jobs sometimes doesn't finish in 1m
(instead of under 1 second) and gets cancelled, causing flaky failures.
Go with Linux and an install phase (of 15s) instead.

Examples:
https://github.com/curl/curl/actions/runs/19558021722/job/56004334495

Closes #19634

diff --git a/.github/workflows/checksrc.yml b/.github/workflows/checksrc.yml
index 32f825214d6c9208eacf79b14d4b94bcd1dc3d51..2f7b0b0e941c7edd55b10688feef139ed3589051 100644 (file)
--- a/.github/workflows/checksrc.yml
+++ b/.github/workflows/checksrc.yml
@@ -120,9 +120,17 @@ jobs:
 
   xmllint:
     name: 'xmllint'
-    runs-on: macos-latest
+    runs-on: ubuntu-latest
     timeout-minutes: 1
     steps:
+      - name: 'install prereqs'
+        run: |
+          sudo rm -f /etc/apt/sources.list.d/microsoft-prod.list
+          sudo apt-get -o Dpkg::Use-Pty=0 update
+          sudo rm -f /var/lib/man-db/auto-update
+          sudo apt-get -o Dpkg::Use-Pty=0 install \
+            libxml2-utils
+
       - uses: actions/checkout@1af3b93b6815bc44a9784bd300feb67ff0d1eeb3 # v6.0.0
         with:
           persist-credentials: false