feat(ci): improve CI workflows

[paullatzelsperger]

What this PR changes/adds

• adds upstream EDC's stalebot workflow
• adds a nightly build (just compile and test)
• updates dependabot

Why it does that

eventual cleanup

Further notes

List other areas of code that have changed but are not necessarily linked to the main feature. This could be method signature changes, package declarations, bugs that were encountered and were fixed inline, etc.

Linked Issue(s)

Closes # <-- insert Issue number if one exists

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