chore: release candid v0.10.20, candid_parser v0.2.3, didc v0.5.3 (#687)

chore: release candid_parser v0.2.2, didc v0.5.2 (#682)

chore: release 2025-07-25 (#653)

- `candid`: 0.10.14 -> 0.10.15
- `candid_derive`: 0.6.6 -> 0.10.15
- `candid_parser`: 0.1.4 -> 0.2.0
- `didc`: 0.4.0 -> 0.5.0