fluffy ci: both testutp and linux test using ubuntu 22.04

to avoid conflict because if testutp using ubuntu-latest
cached Nim compiler will be used by linux test which is using
ubuntu 20.04, then missing glibc 2.33 error. ubuntu 20.04 still
using glibc 2.31

.github/workflows/fluffy.yml

@@ -28,7 +28,7 @@ jobs:
   # separate job so it can run concurrently with other tests
   testutp:
     # whole test setup runs on ubuntu so we do not need multiple arch setup here
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-22.04
     # TODO: for now only push event as this way it is easier to get branch name
     # to build container
     if: github.event_name == 'push'
@@ -108,7 +108,7 @@ jobs:
         include:
           - target:
               os: linux
-            builder: ubuntu-20.04
+            builder: ubuntu-22.04
             shell: bash
           - target:
               os: macos