Build failed on arm v7

[sinegar]

Postgresql seems to fail to start:

• https://github.com/izer-xyz/3cx-docker/runs/3359956322?check_suite_focus=true

[sinegar]

Issue:

• Postgres port already in use

Root cause:

• Parallel build (buildx) shares the same network (probably host)

Workaround:

• Disable parallel run via buildkit config file (config)

Solution:

• Change networking default settings (driver-opt)

[sinegar]

Closing issue as sequential build works okay. Driver-opt could be investigated to speed up the build process.