Update: update go mod and remove old CI

[vcaesar]

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Description

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[Copilot]

Pull request overview

Cleans up legacy CI artifacts and refreshes a core dependency used by the dictionary trie implementation.

Changes:

• Bumped github.com/vcaesar/cedar dependency from v0.20.2 to v0.30.0.
• Removed the deprecated Travis CI configuration and updated README badges accordingly.
• Updated go.sum checksums to match the new dependency version.

Reviewed changes

Copilot reviewed 5 out of 6 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
README.md	Disables the Travis CI badge (now commented out).
README_zh.md	Removes the Travis CI badge from the Chinese README.
README_ja.md	Removes the Travis CI badge from the Japanese README.
go.mod	Updates github.com/vcaesar/cedar to v0.30.0.
go.sum	Updates checksums for the new cedar version.
.travis.yml	Deletes the legacy Travis CI configuration file.

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