umami: skip pnpmDeps from other platforms

When fetching dependencies for all platforms (default for pnpm.fetchDeps)
the pnpmDeps derivation size increases to over 4GiB, which is above the
limit allowed by Hydra, failing the build there.
This commit removes the `--force` flag when executing `pnpm install`, so
only dependencies for the current platform are fetched and installed.

pkgs/by-name/um/umami/package.nix

@@ -87,18 +87,24 @@ stdenvNoCC.mkDerivation (finalAttrs: {
     hash = "sha256-rkOD52suE6bihJqKvMdIvqHRIcWhSxXzUkCfmdNbC40=";
   };
 
-  # install dev dependencies as well, for rollup
-  pnpmInstallFlags = [ "--prod=false" ];
-
   pnpmDeps = pnpm.fetchDeps {
     inherit (finalAttrs)
       pname
-      pnpmInstallFlags
       version
       src
       ;
+    # prevent downloading dependencies for windows
+    # which bloat derivation size and fail to build on hydra
+    # https://github.com/NixOS/nixpkgs/pull/467820#issuecomment-3624054271
+    pnpmInstallFlags = [
+      "--force=false"
+      "--os=linux"
+      "--os=darwin"
+      "--cpu=x64"
+      "--cpu=arm64"
+    ];
     fetcherVersion = 2;
-    hash = "sha256-eXurT8kfVJcJoFunrt7h8LKuhsIhGrYDW6shvGA6GXY=";
+    hash = "sha256-bqeJ0wzCtnuR6V67Qe1N9UcaHPLziuBhsn7eN8JVJbQ=";
   };
 
   env.CYPRESS_INSTALL_BINARY = "0";