Remove unused NoVersionFound exception

[farhannadim311]

Description

Removes the unused NoVersionFound exception class from boto3/exceptions.py.

Motivation

The NoVersionFound exception was added in October 2014 (commit 7600fa4) during a refactoring to use Botocore's data loader, but it was never actually used anywhere in the codebase. The exception class has a comment noting it's safe to remove:

NOTE: This doesn't appear to be used anywhere.

It's probably safe to remove this.

class NoVersionFound(Boto3Error):
pass## Verification

• ✅ Searched the entire codebase: NoVersionFound is not imported or referenced anywhere
• ✅ The functionality it was intended for is handled by UnknownAPIVersionError, which is actively used in session.py
• ✅ No documentation references this exception
• ✅ No tests reference this exception

Impact

• Breaking change: No - this exception was never part of the public API
• Documentation: No changes needed - it was never documented
• Tests: No test changes needed - it was never tested

This is a simple code cleanup that removes dead code, making the codebase easier to maintain.