Fix format CI failure by applying Black-compliant formatting in adicts/functions.py

[Copilot]

The format GitHub Actions job failed because black --check --target-version=py314 adicts/ detected a non-compliant line in adicts/functions.py. This PR applies the minimal formatting update needed for the check run (82699394730) to pass.

• Root cause

  • black reported exactly one file requiring reformat: adicts/functions.py.

• Code change

  • Reflowed the d_multiply function signature into Black’s multiline style (no logic/behavior changes).

• Impact

  • Formatting-only diff; runtime behavior remains unchanged.

def d_multiply(
    d: Mapping[A, Numeric], dmul: Mapping[A, Numeric]
) -> Mapping[A, Numeric]: