Could not find a version that satisfies the requirement psycopg code example

Example: Could not find a version that satisfies the requirement psycopg2>=2.8 (from pgcli) (from versions: 2.7.5, 2.7.6, 2.7.6.1, 2.7.7)

pip install pgcli==2.1.1 --only-binary psycopg2