chore(): update the dependencies mercurius for compatibility with fastify v5.x 🔥

[Tony133]

PR Checklist

Please check if your PR fulfills the following requirements:

• The commit message follows our guidelines: https://github.com/nestjs/nest/blob/master/CONTRIBUTING.md
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

PR Type

What kind of change does this PR introduce?

• Bugfix
• Feature
• Code style update (formatting, local variables)
• Refactoring (no functional changes, no api changes)
• Build related changes
• CI related changes
• Other... Please describe:

What is the current behavior?

Issue Number:

• chore(deps): update dependency mercurius to v15 #3336
• chore(deps): update dependency @mercuriusjs/federation to v4 #3326
• chore(deps): update dependency @mercuriusjs/gateway to v4 #3327
• chore(deps): update dependency fastify to v5 #3335

What is the new behavior?

Proposal:

• Update the dependencies mercurius for compatibility with fastify v5.x 🔥

Does this PR introduce a breaking change?

• Yes
• No

Other information