ci/contributing: verify donation address/qr's are signed

[plowsof]

with this PR i have moved the general fund donation addresses/qr checksums into a _data file that can be signed. this is confirmed in the workflow

thoughts? if this is useful we can ask bF to verify/sign the file.

• [x] Btc QR code with a consistent address
• [x] Confirm _data is gpg signed
• [x] Check hashes of QR's
• [x] Confirm scanned QR content == expected
• [x] Monero QR now has "monero:" uri
• [ ] After review ask bF to sign the file

to sign: (whilst in _data) gpg --output contributing.yml.asc --armor --detach-sig contributing.yml overwrite existing file :heavy_check_mark: