Melange getting started fails on step 4

[jitto]

Describe the bug
https://edu.chainguard.dev/open-source/build-tools/melange/getting-started-with-melange/ step 4 fails to build the apk - because the provided melange.yaml in step 3 expects php81 to be available in alpine edge main or community repositories. But php81 is only available in testing.

To Reproduce
Steps to reproduce the behavior:

1. Go to https://edu.chainguard.dev/open-source/build-tools/melange/getting-started-with-melange/
2. Do all the steps as documented
3. See error in step 4 when building apk

Expected behavior
Step 4 is expected to build an apk and not error out

Screenshots
If applicable, add screenshots to help explain your problem.

Desktop (please complete the following information):

• OS: Linux - Pop!_OS 22.04 LTS
• Browser - chrome
• Version - 125

Additional context
By changing the melange.yaml to add repository https://dl-cdn.alpinelinux.org/alpine/edge/testing I was able to build the apk.