Compile-time errors after updating Xcode to v15

[shishir2sr]

Issue Description

After updating my Xcode to version 15, I've encountered compile-time errors in multiple places within the codebase of the package. These errors seem to be related to type conversion and specialization. I'm reaching out to report these issues and seek assistance in resolving them.

Error 1

Cannot convert return expression of type 'Observable' to return type 'Observable<Element.Element>'

Error 2

Cannot specialize non-generic type 'Observable'

These errors are occurring in eight different locations across the package's codebase, particularly in the cascade.swift and distinct.swift files.

Steps to Reproduce:

1. Upgrade Xcode to version 15.
2. Attempt to build or compile the package.

Expected Behavior:

The package should build and compile successfully without any type-related errors.

Actual Behavior:

Compile-time errors, as described above, prevent successful compilation.

[vzsg]

A fix has already been released as version 6.2.1 for that error.
Is your project up to date?