Python: Update README.md (#10028)

prompt_template_config needs PromptTemplateConfig type but req_settings
is PromptExecutionSettings type which seems to be accepted better by
prompt_execution_settings

### Motivation and Context

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  It's a README fix :) 

### Description

prompt_template_config needs PromptTemplateConfig type but req_settings
is PromptExecutionSettings type which seems to be accepted better by
prompt_execution_settings

Changed to prompt_execution_settings=req_settings instead of
prompt_template_config=req_settings,

### Contribution Checklist

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- [x] The code builds clean without any errors or warnings
- [x] The PR follows the [SK Contribution
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raises no violations
- [x] All unit tests pass, and I have added new tests where possible
- [x] I didn't break anyone 😄

python/README.md

@@ -121,7 +121,7 @@ summarize = kernel.add_function(
     function_name="tldr_function",
     plugin_name="tldr_plugin",
     prompt="{{$input}}\n\nOne line TLDR with the fewest words.",
-    prompt_template_settings=req_settings,
+    prompt_execution_settings=req_settings,
 )
 
 # Summarize the laws of thermodynamics