Upgrade Polkadot JS API to v1.9.1

[mariopino]

Closes #109

Description:

Upgrade Polkadot JS API to v1.9.1.

Problem found in block listener:

crawler_1         | [PolkaStats backend v3] - Block listener - Error adding block #1767669: error: invalid input syntax for type bigint: "undefined", sql: INSERT INTO block (
crawler_1         |             block_number,
crawler_1         |             block_author,
crawler_1         |             block_author_name,
crawler_1         |             block_hash,
crawler_1         |             parent_hash,
crawler_1         |             extrinsics_root,
crawler_1         |             state_root,
crawler_1         |             current_era,
crawler_1         |             current_index,
crawler_1         |             era_length,
crawler_1         |             era_progress,
crawler_1         |             is_epoch,
crawler_1         |             session_length,
crawler_1         |             session_per_era,
crawler_1         |             session_progress,
crawler_1         |             validator_count,
crawler_1         |             spec_name,
crawler_1         |             spec_version,
crawler_1         |             total_events,
crawler_1         |             num_transfers,
crawler_1         |             new_accounts,
crawler_1         |             timestamp
crawler_1         |           ) VALUES (
crawler_1         |             '1767669',
crawler_1         |             'HU1Sesu16xVg9vqSwgCy6idUFaVvDANdERqH9U85634xhxX',
crawler_1         |             '',
crawler_1         |             '0x3dab945ecf7488636760000919bec8e2f4500c34570cd7546b29aa1955ff8e4c',
crawler_1         |             '0x9a0f0f928eb2852434707b82308fe2bc099e837691b74fe6aeab122c4156e719',
crawler_1         |             '0x3795540fc42da6b348ee531639efc6fbda088e8694efbd18d8d09a60549b6a94',
crawler_1         |             '0xa878866a6aadde74bf8034b49107ff88397d846b81eb18c9a79f19d5379d7646',
crawler_1         |             '633',
crawler_1         |             '3110',
crawler_1         |             '3600',
crawler_1         |             'undefined',
crawler_1         |             'true',
crawler_1         |             '600',
crawler_1         |             '6',
crawler_1         |             'undefined',
crawler_1         |             '180',
crawler_1         |             'kusama',
crawler_1         |             '1055',
crawler_1         |             '9',
crawler_1         |             '1',
crawler_1         |             '1',
crawler_1         |             '1586161392006'
crawler_1         |           )

Thank you! 🚀

---

For contributor:

• [ ] Reviewed Files changed in the github PR explorer
• [ ] Attach screenshots of the UI components on the PR description (if applicable)
• [ ] Scope of work approved for big PRs

For reviewer:

• [ ] Manually tested the changes on the UI

[mariopino]

Outdated! :-/