Drop support for Ubuntu 18.04

diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index ef569e3e17fc56d98453dc0ac3aadc7afa15ba96..65ebe5c2d5b27a085baded6cd3db5a4fb4fb8cf5 100644 (file)
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -7,7 +7,7 @@ jobs:
     name: Ubuntu ${{ matrix.ubuntu }}, Ruby ${{ matrix.ruby }}
     strategy:
       matrix:
-        ubuntu: [18.04, 20.04]
+        ubuntu: [20.04]
         ruby: [2.7, 3.0]
     runs-on: ubuntu-${{ matrix.ubuntu }}
     env: