iso: fix replaceStrings length mismatch in cleanVersion

builtins.replaceStrings requires the 'from' and 'to' lists to have the
same length. The 'to' list had a single empty string while 'from' had
three entries (v, newline, CR), which made evaluating image.baseName
fail with: 'from' and 'to' arguments passed to builtins.replaceStrings
have different lengths. Add the two missing empty strings.

Co-authored-by: arena-agent <297053741+arena-agent@users.noreply.github.com>

iso/common.nix

@@ -9,7 +9,7 @@ let
                 else "dev";
 
   # Clean version (remove 'v' prefix and newlines)
-  cleanVersion = builtins.replaceStrings ["v" "\n" "\r"] [""] versionFile;
+  cleanVersion = builtins.replaceStrings ["v" "\n" "\r"] ["" "" ""] versionFile;
 
   pythonEnv = pkgs.python3.withPackages (ps: [ ps.pygobject3 ps.pycairo ]);