Modernize CI/CD pipeline and fix clippy warnings

[sile]

No description provided.

[Copilot]

Pull Request Overview

This PR modernizes the codebase by improving lifetime elision syntax, refactoring generic trait bounds for better clarity, and updating CI/CD infrastructure from Travis CI to GitHub Actions.

Key changes:

• Refactored generic type parameter bounds to place ?Sized with Ord in the where clause for consistency
• Added explicit lifetime parameters ('_) to iterator return types for clarity
• Migrated CI from Travis CI to GitHub Actions with streamlined workflows
• Replaced deprecated map_or(false, ...) pattern with is_some_and() method

Reviewed Changes

Copilot reviewed 10 out of 10 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
src/vec_like.rs	Updated generic bounds and added explicit lifetime elision in iterator return types
src/tree_core.rs	Refactored generic bounds, removed unused std::u32 import, and replaced map_or with is_some_and
src/set.rs	Consistently moved ?Sized to where clause across all generic methods and updated iterator lifetime annotations
src/map.rs	Applied consistent generic bound patterns and explicit lifetime parameters for iterators and entry types
src/heap.rs	Added explicit lifetime parameter to iterator return type
README.md	Updated CI badges from Travis CI to GitHub Actions
Cargo.toml	Removed deprecated Travis CI and Codecov badge configurations
.travis.yml	Removed entire Travis CI configuration file
.github/workflows/release.yml	Added new GitHub Actions workflow for automated releases
.github/workflows/ci.yml	Simplified and modernized CI workflow using GitHub Actions

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.