Run tests against latest/multiple versions of SDK

Right now we only run our tests against a single, pinned version of the SDK. There's a couple of potential issues with this :

1. When a new version of the SDK comes out we have to be watching for that and then update our tests to use the new version. This could mean we miss breaking changes being made (such as https://github.com/Azure/azure-functions-sql-extension/issues/263)
2. Only testing against one version of the runtime means we might miss issues that only occur in one version or another

We should expand our test coverage to include testing all supported versions of the SDK/runtime

No files, tests, or CI entry points are named. Start by locating the current pinned SDK/runtime test configuration and test entry point, then determine which supported versions must be included; done means the test suite runs against all supported versions and exposes version-specific failures.

Written by the indexing model from the issue text.