try Ubuntu 24.04 again

We had problems with their image last time. Let's see if they're
fixed now.

Author: geekosaur

.github/workflows/validate.yml

@@ -53,7 +53,7 @@ jobs:
       matrix:
         sys:
           - { os: windows-latest, shell: "C:/msys64/usr/bin/bash.exe -e {0}" }
-          - { os: ubuntu-22.04, shell: bash }
+          - { os: ubuntu-latest, shell: bash }
           - { os: macos-latest, shell: bash }
         # If you remove something from here, then add it to the old-ghcs job.
         # Also a removed GHC from here means that we are actually dropping
@@ -245,14 +245,15 @@ jobs:
 
   validate-old-ghcs:
     name: Validate old ghcs ${{ matrix.extra-ghc }}
+    # latest/latest doesn't have the old packages the old ghcs depend on
     runs-on: ubuntu-22.04
     needs: validate
 
     strategy:
       matrix:
         extra-ghc:
           ["8.4.4", "8.2.2", "8.0.2"]
-          ## GHC 7.10.3 does not install on ubuntu-22.04 with ghcup.
+          ## GHC 7.10.3 does not install on ubuntu-latest with ghcup.
           ## Older GHCs are not supported by ghcup in the first place.
       fail-fast: false
 
@@ -383,7 +384,7 @@ jobs:
       matrix:
         sys:
           - { os: windows-latest, shell: "C:/msys64/usr/bin/bash.exe -e {0}" }
-          - { os: ubuntu-22.04, shell: bash }
+          - { os: ubuntu-latest, shell: bash }
           - { os: macos-latest, shell: bash }
         # We only use one ghc version the used one for the next release (defined at top of the workflow)
         # We need to build an array dynamically to inject the appropiate env var in a previous job,