Dependency_pins does not honor passwords

[yippie]

Describe the bug

If a package requires an install key, putting a dependency pin on it will fail to install with an invalid install key issue. Including password_env_name in the pin causes a parsing error.

Please add support for install keys on pinned dependencies

Reproduction steps

1. Have a dependency that requires an Install key
2. Add dependency to the dependency_pins section
3. Run update_dependencies

Install will fail due to missing install key.

Your CumulusCI and Python versions

CumulusCI version: 3.77.0
Python version: 3.10.9

Operating System

macOS 13.4.1 (22F82)

Windows environment

No response

CumulusCI installation method

pipx

Error Gist

No response

Additional information

No response

[rygramer]

+1 for this feature fix