fix(client): elide content type header on requests without body

Author: stainless-app[bot]

lib/lithic/internal/transport/base_client.rb

@@ -306,6 +306,8 @@ def initialize(
               Lithic::Internal::Util.deep_merge(*[req[:body], opts[:extra_body]].compact)
             end
 
+          headers.delete("content-type") if body.nil?
+
           url = Lithic::Internal::Util.join_parsed_uri(
             @base_url_components,
             {**req, path: path, query: query}

test/lithic/client_test.rb

@@ -213,8 +213,8 @@ def test_client_redirect_307
       assert_equal(recorded.method, _1.method)
       assert_equal(recorded.body, _1.body)
       assert_equal(
-        recorded.headers.transform_keys(&:downcase).fetch("content-type"),
-        _1.headers.transform_keys(&:downcase).fetch("content-type")
+        recorded.headers.transform_keys(&:downcase)["content-type"],
+        _1.headers.transform_keys(&:downcase)["content-type"]
       )
     end
   end
@@ -301,8 +301,9 @@ def test_default_headers
     lithic.cards.create(type: :VIRTUAL)
 
     assert_requested(:any, /./) do |req|
-      headers = req.headers.transform_keys(&:downcase).fetch_values("accept", "content-type")
-      headers.each { refute_empty(_1) }
+      headers = req.headers.transform_keys(&:downcase)
+      expected = req.body.nil? ? ["accept"] : %w[accept content-type]
+      headers.fetch_values(*expected).each { refute_empty(_1) }
     end
   end
 end