Error for dotproduct metric in PineconeDocumentStore

[jamescalam]

Describe the bug
The PineconeDocumentStore consumes "dot_product" as a similarity metric, Pinecone consumes "dotproduct" as a metric, creating a mismatch and making dot product impossible to use.

Error message

ApiException: (400)
Reason: Bad Request
HTTP response headers: HTTPHeaderDict({'content-type': 'text/plain; charset=utf-8', 'content-length': '38', 'date': 'Tue, 03 May 2022 21:25:59 GMT', 'server': 'envoy', 'x-envoy-upstream-service-time': '1'})
HTTP response body: Metric 'dot_product' is not supported.

Expected behavior
"dot_product" metric should not raise error

Additional context
N/A

To Reproduce

from haystack.document_stores import PineconeDocumentStore

document_store = PineconeDocumentStore(
    api_key='<YOUR_API_KEY>',
    index='document',
    similarity="dot_product",
    embedding_dim=128
)

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System:

• OS: Mac
• GPU/CPU: CPU
• Haystack version (commit or version number): 1.3.0
• DocumentStore: PineconeDocumentStore
• Reader: N/A
• Retriever: N/A

[jamescalam]

I will be submitting a PR to fix soon

[jamescalam]

Above PR should solve the issue