chore(tracing): prepare v0.7.21 release

[JohnTitor]

PR Type

INSERT_PR_TYPE

PR Checklist

• Tests for the changes have been added / updated.
• Documentation comments have been added / updated.
• A changelog entry has been made for the appropriate packages.
• Format code with the nightly rustfmt (cargo +nightly fmt).

Overview

This is the first release from this repository. No functional changes but this will update the metadata and links to point to this repo (and to make sure moving has no problem).
cc @LukeMathWalker for awareness

[JohnTitor]

Note: v0.7.20 was out while moving is ongoing: https://github.com/LukeMathWalker/tracing-actix-web/releases/tag/v0.7.20

[Copilot]

Pull request overview

This PR prepares version 0.7.21 for release following the repository's migration from actix/tracing-actix-web to actix/actix-extras. The changes update metadata, documentation links, and standardize spelling conventions.

Changes:

• Version bumped from 0.7.19 to 0.7.21 in Cargo.toml and Cargo.lock
• GitHub repository URLs updated from actix/tracing-actix-web to actix/actix-extras in documentation
• British to American English spelling standardization in README.md (customisation→customization, popularised→popularized, initialise→initialize)
• Removed project-specific .gitignore and GitHub workflow files (consolidation into monorepo structure)
• Added CHANGELOG entry for v0.7.21 documenting the repository move

Reviewed changes

Copilot reviewed 6 out of 7 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
tracing-actix-web/Cargo.toml	Version bump to 0.7.21
tracing-actix-web/src/lib.rs	Updated GitHub URLs in documentation to reflect new repository location
tracing-actix-web/README.md	Updated GitHub URLs and standardized spelling to American English
tracing-actix-web/CHANGELOG.md	Added v0.7.21 and v0.7.20 release entries
tracing-actix-web/.gitignore	Removed (likely consolidated at repository root)
tracing-actix-web/.github/workflows/general.yml	Removed (likely consolidated at repository root)
Cargo.lock	Updated version reference to 0.7.21

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[Copilot]

The markdown link reference [actix] is used but not defined anywhere in the CHANGELOG. This will result in a broken link. Consider either removing the brackets to make it plain text ("actix organization") or adding a link definition at the end of the file, such as [actix]: https://github.com/actix.