update samples, docs

Author: wing328

modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/PythonClientCodegen.java

@@ -425,7 +425,7 @@ public String generatePackageName(String packageName) {
 
     @Override
     public String generatorLanguageVersion() {
-        return "3.7+";
+        return "3.8+";
     }
 
     @Override

samples/client/echo_api/python-disallowAdditionalPropertiesIfNotPresent/README.md

@@ -10,7 +10,7 @@ This Python package is automatically generated by the [OpenAPI Generator](https:
 
 ## Requirements.
 
-Python 3.7+
+Python 3.8+
 
 ## Installation & Usage
 ### pip install

samples/client/echo_api/python/README.md

@@ -10,7 +10,7 @@ This Python package is automatically generated by the [OpenAPI Generator](https:
 
 ## Requirements.
 
-Python 3.7+
+Python 3.8+
 
 ## Installation & Usage
 ### pip install

samples/openapi3/client/petstore/python-aiohttp/README.md

@@ -10,7 +10,7 @@ This Python package is automatically generated by the [OpenAPI Generator](https:
 
 ## Requirements.
 
-Python 3.7+
+Python 3.8+
 
 ## Installation & Usage
 ### pip install

samples/openapi3/client/petstore/python/README.md

@@ -10,7 +10,7 @@ This Python package is automatically generated by the [OpenAPI Generator](https:
 
 ## Requirements.
 
-Python 3.7+
+Python 3.8+
 
 ## Installation & Usage
 ### pip install