Add ARM64 testing

[stasadev]

Is there an existing issue for this?

• I have searched the existing issues

Is your feature request related to a problem?

Some add-ons may not work with ARM64, or have changes, which are not tested on ARM64

• ARM64: Unable to locate package mongodb-database-tools ddev-mongo#35
• Is mac m1 supported ? (macOS ARM M1 (arm64 64 bits) ) ddev-ioncube#36

Describe your solution

Improve the test matrix to also run tests on ubuntu arm64
https://github.com/ddev/ddev-addon-template/blob/main/.github/workflows/tests.yml

Describe alternatives

No response

Additional context

ARM64 is important for DDEV (especially on Macs), and add-ons must have the necessary test coverage.