[WIP]workaround for rubygems v3.6.7

Author: unasuke

lib/itamae/resource/file.rb

@@ -214,7 +214,9 @@ def send_tempfile
 
           if backend.is_a?(Itamae::Backend::Docker)
             run_command(["mkdir", @temppath])
+            ENV["SOURCE_DATE_EPOCH"] = Time.now.to_i.to_s # TODO: workaround for rubygems v3.6.7
             backend.send_file(src, @temppath, user: attributes.user)
+            ENV["SOURCE_DATE_EPOCH"] = nil
             @temppath = ::File.join(@temppath, ::File.basename(src))
           else
             run_command(["touch", @temppath])