You could make use of urlparse, creating a dictionary that matches psycopg's connection arguments:

import psycopg2
from urllib.parse import urlparse

conStr = "postgres://username:password@localhost:5432/data_quality"
p = urlparse(conStr)

pg_connection_dict = {
    'dbname': p.path[1:],
    'user': p.username,
    'password': p.password,
    'port': p.port,
    'host': p.hostname
}

print(pg_connection_dict)
con = psycopg2.connect(**pg_connection_dict)
print(con)

Out:

{'dbname': 'data_quality', 'user': 'username', 'password': 'password', 'port': 5432, 'host': 'localhost'}
<connection object at 0x105f58190; dsn: 'user=xxx password=xxx dbname=xxx host=xxx port=xxx', closed: 0>