chore: bump golang.org/x/crypto and paho.mqtt.golang

[anhuv]

Title

chore: bump golang.org/x/crypto and paho.mqtt.golang

Description

This PR updates a small set of Go dependencies used by Tyk Gateway for maintenance and security reasons.

Update process:

• Ran go get golang.org/x/crypto@v0.46.0
• Ran go get github.com/eclipse/paho.mqtt.golang@v1.5.1
• Ran go mod tidy to ensure module consistency

Updated dependencies:

• golang.org/x/crypto: v0.41.0 → v0.46.0
• github.com/eclipse/paho.mqtt.golang: v1.4.3 → v1.5.1

Changes are limited to go.mod and go.sum.
No functional code changes are included.

Related Issue

Closes #7654

Motivation and Context

These dependencies are actively maintained and receive regular security fixes and stability improvements.
Keeping them up to date helps reduce technical debt and improves long-term compatibility with newer Go versions.

How This Has Been Tested

• go build ./...

Screenshots (if appropriate)

N/A

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Refactoring or add test (improvements in base code or adds test coverage to functionality)

Checklist

• I ensured that the documentation is up to date (no documentation changes required)
• I explained why this PR updates go.mod in detail with reasoning why it's required
• I would like a code coverage CI quality gate exception and have explained why