GitDownloadStrategy: don't pass --depth to fetch

The --depth option is apparently more nuanced that I had originally
thought, and while it does not actually break repositories, repeatedly
using "--depth 1" can cause problems depending on the structure of the
history.

Luckily, we don't actually need it to prevent the entire repository from
being fetched as long as the fetch respec is set correctly, which we do
since 7718c939b06987ff8f1ecd599c8ace6f998ce180.

Fixes Homebrew/homebrew#12024.

Signed-off-by: Jack Nagel <jacknagel@gmail.com>

Library/Homebrew/download_strategy.rb

@@ -360,7 +360,6 @@ class GitDownloadStrategy < AbstractDownloadStrategy
           end
 
         git_args = %w[git fetch origin]
-        git_args << '--depth' << '1' if support_depth?
         quiet_safe_system(*git_args)
       end
     end