CI: remove Ubuntu 18, no longer available on Actions

diff --git a/.github/workflows/ci-tests.yml b/.github/workflows/ci-tests.yml
index 1f6b818c6ee9097833e4ea4d5b434118aaf4d5d3..7d9c931da0b65b5b5a5301f90a38d50bba4a2e31 100644 (file)
--- a/.github/workflows/ci-tests.yml
+++ b/.github/workflows/ci-tests.yml
@@ -37,7 +37,7 @@ jobs:
         needs: create-archive
         strategy:
             matrix:
-                ubuntu: [18, 20, 22]
+                ubuntu: [20, 22]
                 include:
                     - ubuntu: 18
                       postgresql: 9.6