test: test fixes & vulnerability scan

[hallvictoria]

Description

Testing improvements / fixes:

• Pinning to extension versions while running tests. This ensures that we're running our tests using the latest extension versions, regardless of if it's a beta version or not.
• Adding EventGrid source Blob Trigger functions to the blob function app. While the functionality can't be tested here, we can ensure that these functions are being indexed properly.
• Skipping a dependency isolation test that fails when using artifact versions of the SDK / extensions
• Adding a pip-audit step to the pipeline for public and official build
  • When running pip-audit ., pip-audit will be run for every required dependency of the worker (eg: grpc, protobuf, etc.)
  • Since those packages have already been installed, there is no extra re-installation time
• Updates README
• Removes unsigned file from werkzeug dependency

Fixes #

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PR information

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• New Unit tests were added for the changes made and CI is passing.

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