Fix Payload Duplication Bug in build_payloads Function by Copying Metadata for Each Chunk

[suryadevarapranav]

This pull request resolves the Issue #88.

Description

Overview: This pull request addresses the issue of duplicated text in the payloads generated by the build_payloads function. Previously, each payload incorrectly contained the same text due to a shared reference to doc.metadata, which caused in-place updates across all payloads.

Changes Made:

Updated build_payloads to create a shallow copy of doc.metadata for each chunk. This ensures each payload dictionary is independent, containing the correct text for each specific chunk.
Added a comment for clarity.

Testing: Tested the function with multiple chunks, confirming that each payload now contains the expected text and metadata without interference.

Example:

News document from Alpaca.

Payloads uploaded to Qdrant.

Qdrant Query used to verify the issue fix.

POST collections/alpaca_news/points/scroll
{
  "filter": {
    "must": [
      {
        "key": "date",
        "match": {
          "text": "2024-01-01T13:15:32+00:00"
        }
      }
    ]
  }
}

[suryadevarapranav]

Hello @iusztinpaul @Paulescu @Joywalker, Can you please take a look at my pull request, when you find some time?

Thanks,
Deva.