adding python3-fastapi templates

Adding python3-fastapi and python3-fastapi-debian to the templates

Description

It would be awesome to have the fastapi templates in the main repo. I used https://github.com/loudsquelch/openfaas-python3-fastapi-template for my additions and created an alpine and debian version similar to the python3 ones you are providing.

Motivation and Context

The default python3 module is okayish, but with fastapi we can have the advantages of that library in openfaas. I have specified workers 1 to leave the scaling up to openfaas. The /doc route should be exposed as usual and all in all it should provide a better way of integrating APIs with OpenFAAS.

Which issue(s) this PR fixes

How Has This Been Tested?

I deployed both functions to my local OpenFAAS setup and ran the ./verify.sh script

Types of changes

[ ] Bug fix (non-breaking change which fixes an issue)
[x] New feature (non-breaking change which adds functionality)
[ ] Breaking change (fix or feature that would cause existing functionality to change)
[ ] Version change (see: Impact to existing users)

Impact to existing users

Two new templates are added that do not change the existing python3 and python3-debian templates

Checklist:

[x] My code follows the code style of this project.
[ ] My change requires a change to the documentation.
[ ] I have updated the documentation accordingly.
[x] I've read the CONTRIBUTION guide
[ ] I have signed-off my commits with git commit -s
[ ] I have added tests to cover my changes.
[x] All new and existing tests passed.

Thank you for your contribution. unfortunately, one or more of your commits are missing the required "Signed-off-by:" statement. Signing off is part of the Developer Certificate of Origin (DCO) which is used by this project.

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:bulb: Shall we fix this?

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openfaas / templates