update Ubuntu runner to the newer version

Signed-off-by: Mykhailo Kuznietsov <[email protected]>

Author: mkuznyetsov

.github/workflows/publication-builder.yaml

@@ -26,7 +26,7 @@ on:
 jobs:
   build:
     name: Publication builder
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-22.04
     container: "quay.io/eclipse/che-docs:next"
     steps:
       - name: Checkout publication-builder branch