Pin test runner to Ubuntu 18 to un-break CI (pythonGH-24715) (pythonGH-24716)

miss-islington · brandtbucher · web-flow · commit a99860e4022c · 2021-03-03T12:24:05.000-05:00
(cherry picked from commit 94894dd) Co-authored-by: Brandt Bucher <brandt@python.org> Co-authored-by: Brandt Bucher <brandt@python.org>
diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
@@ -73,7 +73,7 @@ jobs:
 
   build_ubuntu:
     name: 'Ubuntu'
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-18.04
     needs: check_source
     if: needs.check_source.outputs.run_tests == 'true'
     env:
