Upgrade Go version to 1.23.6

[rlymbur]

What type of PR is this?
Upgrade

Which issue does this PR fix:
This addresses a make presubmit issue that fails on make vet.

What does this PR do / Why do we need it:
This correctly upgrades the Go version and related dependencies.

If an issue # is not available please add repro steps and logs from aws-gateway-controller showing the issue:
N/A

Testing done on this change:

make presubmit and make e2e-test run successfully.

Automation added to e2e:

N/A

Will this PR introduce any new dependencies?:

No.

Will this break upgrades or downgrades. Has updating a running cluster been tested?:
No.

Does this PR introduce any user-facing change?:

Upgraded Go to 1.23.6 

Do all end-to-end tests successfully pass when running make e2e-test?:

[SynchronizedAfterSuite] /Volumes/workplace/aws-application-networking-k8s/test/suites/integration/suite_test.go:72 {"level":"info","ts":"2025-02-18T13:55:38.560-0800","caller":"test/framework.go:266","msg":"Deleting objects: *v1.Gateway/test-gateway, *v1.Pod/grpc-runner"} {"level":"info","ts":"2025-02-18T13:55:38.735-0800","caller":"test/framework.go:285","msg":"Waiting for NotFound, objects: *v1.Gateway/test-gateway, *v1.Pod/grpc-runner"} [SynchronizedAfterSuite] PASSED [31.791 seconds] ------------------------------ Ran 69 of 69 Specs in 3264.972 seconds SUCCESS! -- 69 Passed | 0 Failed | 0 Pending | 0 Skipped --- PASS: TestIntegration (3264.98s) PASS ok github.com/aws/aws-application-networking-k8s/test/suites/integration 3265.675s 

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[mikestvz]

/LGTM