ci: 6 GB to install, 4 GB to test, 2 vCPUs: lean with headroom

.github/workflows/iso-2-gitea-build.yml

@@ -93,7 +93,7 @@ jobs:
       options: --privileged
     strategy:
       fail-fast: false
-      # The runner has ~20 GB of RAM for this: an install VM takes 4 GB (4 GB once installed too), so two at a time (needs the
+      # The runner has ~20 GB of RAM for this: an install VM takes 6 GB (4 GB once installed), so two at a time (needs the
       # runner's `capacity: 2`; with 1 they run one after the other).
       max-parallel: 2
       matrix:
@@ -134,8 +134,8 @@ jobs:
           VM_TIMEZONE: UTC
           # The runner is 4 cores / 8 threads: two VMs with 2 vCPUs leave 4 threads for the host and the runner.
           VM_CPUS: "2"
-          # RAM of the live installer VM (the ISO is read from its cdrom, only the overlay and the installer use RAM); 8 GB is the local default, this is the lean end: raise it if an install dies out of memory
-          VM_INSTALL_MEM: 4G
+          # RAM of the live installer VM (the ISO is read from its cdrom, only the overlay and the installer use RAM); 8 GB is the local default, lean with headroom: lower it only after a run shows the install stays well under
+          VM_INSTALL_MEM: 6G
           VM_ISO_DIR: ${{ github.workspace }}/iso
         run: |
           mkdir -p ~/.ssh ~/vms/pkg-cache