chore: update readme and scripts with url (#198)

## docs(README)
- add dependency of pgvector
- fix `vector_cos_ops` to `vector_cosine_ops`
- update image version

## chore(bench scripts)
- fix incorrect QPS count at parallel requests
  - when `workers` > 32, QPS will be overestimated
- send the same whole data to all requests, instead of split data for
parallel requests
- for dataset `laion-100`, 1000 split to 128 parts will be have a huge
negative impact on query startup
- use dburl instead of local password

Signed-off-by: cutecutecat <[email protected]>

Author: cutecutecat