🧹 Exclude specs and bin/rails from gem files

There's no need to include the spec files in the gemfile list.  And
including `bin/rails` can wreck havoc on the downstream application.

Related to:

- samvera/hyrax#6146

hyrax-iiif_av.gemspec

@@ -16,7 +16,7 @@ Gem::Specification.new do |s|
   s.license     = 'Apache-2.0'
 
   s.files = `git ls-files -z`.split("\x0").reject do |f|
-    f.match(%r{^(test|spec|features)/})
+    f.match(%r{^(test|spec|features)/}) || f == 'bin/rails'
   end
 
   s.add_dependency "rails", ">= 5.1", "< 8.0"