Drop patch2quilt helper (unused)

As discussed with ft on IRC
README.source: Minor update (outline, rephrasing)

Git-Dch: Ignore
Workflow: Fix pdebuild options

Git-Dch: Ignore
Upload to experimental as 5.0.7-1
Workflow: Update how the "New upstream release" changelog entry should look like
Workflow: Mention to which package dpt belongs

Git-Dch: Ignore