on delete_collection, if the collection does not exist, more clear error is shown

[druskacik]

Description of changes

• Improvements & Bug fixes
  • Clearer error thrown when trying to delete unexisting collection

Test plan

import chromadb

chroma_client = chromadb.Client()
chroma_client.delete_collection('test1')

>>> ...
>>> ValueError: Collection with name test1 does not exist
# Before: IndexError: list index out of range

Documentation Changes

No documentation changes necessary.

[jeffchuber]

@druskacik thanks for this! can you write a test for this?

[druskacik]

@jeffchuber Sure, I added the test and also previously forgotten update to fastapi version.

[jeffchuber]

Closing this because it is very stale, but we will address this.

Issue to track https://github.com/chroma-core/chroma/issues/520