Make stored META data reproducible in CURI

Sort the hash keys to ensure we generate the same JSON dump from the
same source every time. Helps making rakudo and module builds
100 % reproducible.

src/core/CompUnit/Repository/Installation.pm6

@@ -141,7 +141,7 @@ sub MAIN(:$name, :$auth, :$ver, *@, *%) {
                         if $resources-dir.add($files{$file}).e
                         and not $.prefix.add($file).e; # bin/ is already included in the path
                 }
-                $dist-file.spurt: Rakudo::Internals::JSON.to-json(%meta);
+                $dist-file.spurt: Rakudo::Internals::JSON.to-json(%meta, :sorted-keys);
             }
         }
         $.prefix.add('version').spurt('2');
@@ -247,7 +247,7 @@ sub MAIN(:$name, :$auth, :$ver, *@, *%) {
         %meta<files>    = %links;    # add our new name-path => content-id mapping
         %meta<provides> = %provides; # new meta data added to provides
         %!dist-metas{$dist-id} = %meta;
-        $dist-dir.add($dist-id).spurt: Rakudo::Internals::JSON.to-json(%meta);
+        $dist-dir.add($dist-id).spurt: Rakudo::Internals::JSON.to-json(%meta, :sorted-keys);
 
         # reset cached id so it's generated again on next access.
         # identity changes with every installation of a dist.