proxmox scripts: set experimental features rather than implicitly depending on them

Signed-off-by: Kiara Grouwstra <kiara@procolix.eu>

infra/proxmox-provision.sh

@@ -172,7 +172,7 @@ grab_vm_options () {
   printf 'Grabing VM options for VM %s...\n' "$vm_name"
 
   options=$(
-    nix eval \
+    nix --extra-experimental-features 'nix-command flakes' eval \
       --impure --raw --expr "
         builtins.toJSON (builtins.getFlake (builtins.toString ./.)).vmOptions.$vm_name
       " \
@@ -220,7 +220,7 @@ build_iso () {
     nix_host_keys=
   fi
 
-  nix build \
+  nix --extra-experimental-features 'nix-command flakes' build \
     --impure --expr "
       let flake = builtins.getFlake (builtins.toString ./.); in
       import ./infra/makeInstallerIso.nix {

infra/proxmox-remove.sh

@@ -160,7 +160,7 @@ grab_vm_options () {
     printf 'Grabing VM options for VM %s...\n' "$vm_name"
 
     options=$(
-      nix eval \
+      nix --extra-experimental-features 'nix-command flakes' eval \
         --impure --raw --expr "
           builtins.toJSON (builtins.getFlake (builtins.toString ./.)).vmOptions.$vm_name
         " \