Add a Debug release to weekly (in order to conveniently diagnose issues with Valgrind)

[luzpaz]

To help testers report more in-depth errors/warnings through diagnosing issues with Valgrind¹. The alternative is having them build a Debug build themselves and that is:

1. a time consuming obstacle that creates a barrier for entry and engagement
2. documentation on building debug builds is not comprehensive enough

Request mentioned by @huguesdpdn-aerospace in:

• Tutorials on how to use tools like perf and valgrind to increase speed/efficiency and find bugs  DevelopersHandbook#112 (comment)

Footnotes

1. https://valgrind.org/ ↩

[huguesdpdn-aerospace]

To add in the Debug build:
FreeCAD/FreeCAD#16316 (comment)

When building Coin in Debug mode , if there is a Coin version is already installed on the machine that compiles FreeCAD , it may cause this compilation issue and/or behavior