dotnet/update.sh: format output with nixfmt

pkgs/development/compilers/dotnet/update.sh

@@ -1,5 +1,5 @@
 #!/usr/bin/env nix-shell
-#!nix-shell -I nixpkgs=./. -i bash -p curl jq nix gnused
+#!nix-shell -I nixpkgs=./. -i bash -p curl jq nix gnused nixfmt-rfc-style
 # shellcheck shell=bash
 
 set -Eeuo pipefail
@@ -310,7 +310,7 @@ update() {
     aspnetcore_sources="$(platform_sources "$aspnetcore_files")"
     runtime_sources="$(platform_sources "$runtime_files")"
 
-    result=$(mktemp)
+    result=$(mktemp -t dotnet-XXXXXX.nix)
     trap "rm -f $result" TERM INT EXIT
 
     (
@@ -388,9 +388,10 @@ in rec {
         echo "
   sdk_$major_minor_underscore = $latest_sdk;
 }"
-        )> "${result}"
+        )> "$result"
 
-        cp "${result}" "$output"
+    nixfmt "$result"
+    cp "$result" "$output"
     echo "Generated $output"
 }