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