chore: update placeholder string

Author: stainless-app[bot]

test/docker_engine_ruby/resources/images_test.rb

@@ -26,7 +26,7 @@ def test_delete
   def test_build_required_params
     skip("Mock server tests are disabled")
 
-    response = @docker.images.build(body: Pathname(__FILE__))
+    response = @docker.images.build(body: StringIO.new("Example data"))
 
     assert_pattern do
       response => nil
@@ -132,7 +132,7 @@ def test_inspect_
   def test_load__required_params
     skip("Mock server tests are disabled")
 
-    response = @docker.images.load_(body: Pathname(__FILE__))
+    response = @docker.images.load_(body: StringIO.new("Example data"))
 
     assert_pattern do
       response => nil

test/docker_engine_ruby/resources/plugins_test.rb

@@ -6,7 +6,7 @@ class DockerEngineRuby::Test::Resources::PluginsTest < DockerEngineRuby::Test::R
   def test_create_required_params
     skip("Mock server tests are disabled")
 
-    response = @docker.plugins.create(name: "name", body: Pathname(__FILE__))
+    response = @docker.plugins.create(name: "name", body: StringIO.new("Example data"))
 
     assert_pattern do
       response => nil