Make templates multi-arch

[utsavanand2]

Signed-off-by: Utsav Anand utsavanand2@gmail.com

Description

Change the following templates to support multi-arch buildx builds: go node node12 php7 python python3 python3-debian ruby

Motivation and Context

The PR will add the freedom to build and deploy OpenFaaS function to multiple CPU architectures. Functions can be built locally or a CI env like Github Actions which supports buildx, and deployed on most common architectures, like amd64, arm64, or armv7

• [x] I have raised an issue to propose this change (required)

Which issue(s) this PR fixes

Fixes #226

How Has This Been Tested?

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

No user impact to existing users because of the tests we have been running for the incubator templates, running functions across environments and architectures.

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
• [x] 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.

[alexellis]

@Waterdrips you should be able to use this change along with faas-cli publish to get multi-arch functions for OpenFaaS Cloud. Can you have a play and let us know if anything else needs changing?