Fix 404 errors with API update

[brunosanches]

The recent changes to the ENTSOG API have impacted how certain queries return results. I've identified two main issues:

Operational Data Queries with Offset:

Previously, querying operational data with an offset would return a 500 error, as expected. Now, it returns a 404 error, which broke the way the library handles end of data. You can reproduce this issue using this URL.

Disabled hasData Parameter for Operator Point Directions:

The hasData parameter has been disabled when querying for Operator Point Directions, and setting this parameter now results in a 404 error. You can reproduce this issue using this URL.

Changes Made

This pull request addresses issue #17 with the following changes:

• Added handling for 404 errors in the library.
• Removed the hasData parameter from the operator_point_directions methods.

These changes ensure the library correctly handles the new API behavior and prevents errors during data retrieval.

[nhcb]

Thanks, apologies for delaying on this merge for so long.