Fix: Remove accidental editor swap file (#1636)

# Summary

The file `rand_core/src/.le.rs.kate-swp` was unintentionally added in PR
#1626. This commit removes the extraneous file.

# Motivation
This file is a temporary editor swap file and serves no purpose in the
repository. It was likely added accidentally.

# Details
No changes for `CHANGELOG.md` - it is a minor change.

Author: mingulov