[AppService] Unhide Python 3.9 in functionapp create

[Hazhzeng]

Description

Azure Functions team plan to release Python 3.9 preview. We want to unhide the --runtime-version 3.9 in functionapp create --help.

Testing Guide

Test with az functionapp create --help. The help content contains

    --runtime-version                    : The version of the functions runtime stack. Allowed
                                           values for each --runtime are: node -> [8, 10, 12, 14
                                           (preview)], java -> [8, 11], powershell -> [7.0], python
                                           -> [3.6, 3.7, 3.8, 3.9 (preview)].

History Notes

[AppService] Allow customer to create Python 3.9 function app

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[Hazhzeng]

cc: @anirudhgarg @vrdmr @pragnagopa @stefanushinardi

[pragnagopa]

please send PR to https://github.com/pragnagopa/azure-functions-supported-runtime-stacks

[yonzhan]

AppService

[yungezz]

hi @Hazhzeng could you pls look at CI failure, after CI passed we can move forward to merge the PR? thanks

[Hazhzeng]

/azp run

[azure-pipelines]

Commenter does not have sufficient privileges for PR 16296 in repo Azure/azure-cli

[Hazhzeng]

Hi @yungezz @qwordy, sorry for the late reply.
I've merged the latest updates on the dev branch and the PR now passes the tests.
Please merge this PR to dev and mark this into S180. Thanks

[qwordy]

Official Release: 12/29/2020