Bug Fixes

• Removed unused imports (thanks @Avasam).
• Avoid to use fcntl module on some environments (thanks @i2y).
• Change a test behavior for unix_connect.get_socket (thanks @i2y).
• Fix accidental data change (thanks @Avasam).
• Prefer bool over Literal[0, 1, None] (thanks @Avasam).
• Change parentheses to brackets in LICENSE (thanks @mtelka).