[ python-fastapi] minor improvements

[wing328]

• minor improvements
• better code format
• update samples

PR checklist

• Read the contribution guidelines.
• Pull Request title clearly describes the work in the pull request and Pull Request description provides details about how to validate the work. Missing information here may result in delayed response from the community.
• Run the following to build the project and update samples:

  ./mvnw clean package 
  ./bin/generate-samples.sh
  ./bin/utils/export_docs_generators.sh
  

  Commit all changed files.
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cc @taxpon (2017/07) @frol (2017/07) @mbohlool (2017/07) @cbornet (2017/09) @kenjones-cisco (2017/11) @tomplus (2018/10) @Jyhess (2019/01) @arun-nalla (2019/11) @spacether (2019/11)

[krjakbrjak]

@wing328 Thanks for fixing the code style and docs. Also marking it beta is a good thing I guess.

I found a typo in my original PR, you might consider adding it to this PR (or of course I can submit another one):

--- a/modules/openapi-generator/src/main/resources/python-fastapi/security_api.mustache
+++ b/modules/openapi-generator/src/main/resources/python-fastapi/security_api.mustache
@@ -34,7 +34,7 @@ oauth2_password = OAuth2PasswordBearer(
 oauth2_code = OAuth2AuthorizationCodeBearer(
     authorizationUrl="{{authorizationUrl}}",
     tokenUrl="{{tokenUrl}}",
-    refreshUrlUrl="{{refreshUrl}}",
+    refreshUrl="{{refreshUrl}}",
     scopes={
 {{#scopes}}
         "{{scope}}": "{{description}}",

[wing328]

@krjakbrjak done via 49e2e14