chore(deps): update rust crate clap_mangen to v0.2.20 #77

Job	Run time
cargo check (ubuntu-latest)	18s
Code Coverage (ubuntu-latest, unix)	1m 54s
cargo clippy -- -D warnings (ubuntu-latest)	12s
cargo check (macOS-latest)	20s
Code Coverage (macos-latest, macos)	1m 44s
cargo clippy -- -D warnings (macOS-latest)	21s
Code Coverage (windows-latest, windows)	2m 13s
cargo check (windows-latest)	1m 33s
cargo clippy -- -D warnings (windows-latest)	17s
cargo fmt --all -- --check	14s
cargo test (ubuntu-latest)	30s
cargo test (macOS-latest)	26s
cargo test (windows-latest)	1m 43s
	11m 45s

Provide feedback